Split GoogleUtilities from FirebaseCore (#1370)

20 files changed, 39 insertions, 2381 deletions

diff --git a/Firebase/Core/FIRApp.m b/Firebase/Core/FIRApp.m
index 2ea7f6b..9f698cf 100644
--- a/Firebase/Core/FIRApp.m
+++ b/Firebase/Core/FIRApp.m
@@ -23,7 +23,6 @@
 #import "Private/FIRCoreConfigurable.h"
 #import "Private/FIRLogger.h"
 #import "Private/FIROptionsInternal.h"
-#import "third_party/FIRAppEnvironmentUtil.h"
 
 NSString *const kFIRServiceAdMob = @"AdMob";
 NSString *const kFIRServiceAuth = @"Auth";
diff --git a/Firebase/Core/FIRLogger.m b/Firebase/Core/FIRLogger.m
index 2784ae9..dbec728 100644
--- a/Firebase/Core/FIRLogger.m
+++ b/Firebase/Core/FIRLogger.m
@@ -14,16 +14,11 @@
 
 #import "Private/FIRLogger.h"
 
-#import "FIRLoggerLevel.h"
-#import "Private/FIRVersion.h"
-#import "third_party/FIRAppEnvironmentUtil.h"
+#import <FirebaseCore/FIRLoggerLevel.h>
+#import <GoogleUtilities/GULAppEnvironmentUtil.h>
+#import <GoogleUtilities/GULLogger.h>
 
-#include <asl.h>
-#include <assert.h>
-#include <stdbool.h>
-#include <sys/sysctl.h>
-#include <sys/types.h>
-#include <unistd.h>
+#import "Private/FIRVersion.h"
 
 FIRLoggerService kFIRLoggerABTesting = @"[Firebase/ABTesting]";
 FIRLoggerService kFIRLoggerAdMob = @"[Firebase/AdMob]";
@@ -51,24 +46,11 @@ NSString *const kFIRLoggerForceSDTERRApplicationArgument = @"-FIRLoggerForceSTDE
 /// Key for the debug mode bit in NSUserDefaults.
 NSString *const kFIRPersistedDebugModeKey = @"/google/firebase/debug_mode";
 
-/// ASL client facility name used by FIRLogger.
-const char *kFIRLoggerASLClientFacilityName = "com.firebase.app.logger";
-
-/// Keys for the number of errors and warnings logged.
-NSString *const kFIRLoggerErrorCountKey = @"/google/firebase/count_of_errors_logged";
-NSString *const kFIRLoggerWarningCountKey = @"/google/firebase/count_of_warnings_logged";
-
-static dispatch_once_t sFIRLoggerOnceToken;
-
-static aslclient sFIRLoggerClient;
-
-static dispatch_queue_t sFIRClientQueue;
-
 /// NSUserDefaults that should be used to store and read variables. If nil, `standardUserDefaults`
 /// will be used.
 static NSUserDefaults *sFIRLoggerUserDefaults;
 
-static BOOL sFIRLoggerDebugMode;
+static dispatch_once_t sFIRLoggerOnceToken;
 
 // The sFIRAnalyticsDebugMode flag is here to support the -FIRDebugEnabled/-FIRDebugDisabled
 // flags used by Analytics. Users who use those flags expect Analytics to log verbosely,
@@ -76,8 +58,6 @@ static BOOL sFIRLoggerDebugMode;
 // that behavior.
 static BOOL sFIRAnalyticsDebugMode;
 
-static FIRLoggerLevel sFIRLoggerMaximumLevel;
-
 #ifdef DEBUG
 /// The regex pattern for the message code.
 static NSString *const kMessageCodePattern = @"^I-[A-Z]{3}[0-9]{6}$";
@@ -86,96 +66,53 @@ static NSRegularExpression *sMessageCodeRegex;
 
 void FIRLoggerInitializeASL() {
   dispatch_once(&sFIRLoggerOnceToken, ^{
-    NSInteger majorOSVersion = [[FIRAppEnvironmentUtil systemVersion] integerValue];
-    uint32_t aslOptions = ASL_OPT_STDERR;
-#if TARGET_OS_SIMULATOR
-    // The iOS 11 simulator doesn't need the ASL_OPT_STDERR flag.
-    if (majorOSVersion >= 11) {
-      aslOptions = 0;
-    }
-#else
-    // Devices running iOS 10 or higher don't need the ASL_OPT_STDERR flag.
-    if (majorOSVersion >= 10) {
-      aslOptions = 0;
-    }
-#endif  // TARGET_OS_SIMULATOR
+    // Register Firebase Version with GULLogger.
+    GULLoggerRegisterVersion(FIRVersionString);
 
     // Override the aslOptions to ASL_OPT_STDERR if the override argument is passed in.
     NSArray *arguments = [NSProcessInfo processInfo].arguments;
-    if ([arguments containsObject:kFIRLoggerForceSDTERRApplicationArgument]) {
-      aslOptions = ASL_OPT_STDERR;
-    }
-
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wdeprecated-declarations"  // asl is deprecated
-    // Initialize the ASL client handle.
-    sFIRLoggerClient = asl_open(NULL, kFIRLoggerASLClientFacilityName, aslOptions);
-
-    // Set the filter used by system/device log. Initialize in default mode.
-    asl_set_filter(sFIRLoggerClient, ASL_FILTER_MASK_UPTO(ASL_LEVEL_NOTICE));
-    sFIRLoggerDebugMode = NO;
-    sFIRAnalyticsDebugMode = NO;
-    sFIRLoggerMaximumLevel = FIRLoggerLevelNotice;
+    BOOL overrideSTDERR = [arguments containsObject:kFIRLoggerForceSDTERRApplicationArgument];
 
     // Use the standard NSUserDefaults if it hasn't been explicitly set.
     if (sFIRLoggerUserDefaults == nil) {
       sFIRLoggerUserDefaults = [NSUserDefaults standardUserDefaults];
     }
 
+    BOOL forceDebugMode = NO;
     BOOL debugMode = [sFIRLoggerUserDefaults boolForKey:kFIRPersistedDebugModeKey];
     if ([arguments containsObject:kFIRDisableDebugModeApplicationArgument]) {  // Default mode
       [sFIRLoggerUserDefaults removeObjectForKey:kFIRPersistedDebugModeKey];
     } else if ([arguments containsObject:kFIREnableDebugModeApplicationArgument] ||
                debugMode) {  // Debug mode
       [sFIRLoggerUserDefaults setBool:YES forKey:kFIRPersistedDebugModeKey];
-      asl_set_filter(sFIRLoggerClient, ASL_FILTER_MASK_UPTO(ASL_LEVEL_DEBUG));
-      sFIRLoggerDebugMode = YES;
-    }
-
-    // We should disable debug mode if we are running from App Store.
-    if (sFIRLoggerDebugMode && [FIRAppEnvironmentUtil isFromAppStore]) {
-      sFIRLoggerDebugMode = NO;
+      forceDebugMode = YES;
     }
-
-    sFIRClientQueue = dispatch_queue_create("FIRLoggingClientQueue", DISPATCH_QUEUE_SERIAL);
-    dispatch_set_target_queue(sFIRClientQueue,
-                              dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0));
-
-#ifdef DEBUG
-    sMessageCodeRegex =
-        [NSRegularExpression regularExpressionWithPattern:kMessageCodePattern options:0 error:NULL];
-#endif
+    GULLoggerInitializeASL(overrideSTDERR, forceDebugMode);
   });
 }
 
-void FIRSetAnalyticsDebugMode(BOOL analyticsDebugMode) {
-  FIRLoggerInitializeASL();
-  dispatch_async(sFIRClientQueue, ^{
-    // We should not enable debug mode if we are running from App Store.
-    if (analyticsDebugMode && [FIRAppEnvironmentUtil isFromAppStore]) {
-      return;
-    }
-    sFIRAnalyticsDebugMode = analyticsDebugMode;
-    asl_set_filter(sFIRLoggerClient, ASL_FILTER_MASK_UPTO(ASL_LEVEL_DEBUG));
-  });
+__attribute__((no_sanitize("thread"))) void FIRSetAnalyticsDebugMode(BOOL analyticsDebugMode) {
+  sFIRAnalyticsDebugMode = analyticsDebugMode;
 }
 
 void FIRSetLoggerLevel(FIRLoggerLevel loggerLevel) {
-  if (loggerLevel < FIRLoggerLevelMin || loggerLevel > FIRLoggerLevelMax) {
-    FIRLogError(kFIRLoggerCore, @"I-COR000023", @"Invalid logger level, %ld", (long)loggerLevel);
-    return;
-  }
   FIRLoggerInitializeASL();
-  // We should not raise the logger level if we are running from App Store.
-  if (loggerLevel >= FIRLoggerLevelNotice && [FIRAppEnvironmentUtil isFromAppStore]) {
-    return;
-  }
+  GULSetLoggerLevel((GULLoggerLevel)loggerLevel);
+}
 
-  sFIRLoggerMaximumLevel = loggerLevel;
-  dispatch_async(sFIRClientQueue, ^{
-    asl_set_filter(sFIRLoggerClient, ASL_FILTER_MASK_UPTO(loggerLevel));
-  });
+#ifdef DEBUG
+void FIRResetLogger() {
+  extern void GULResetLogger(void);
+  sFIRLoggerOnceToken = 0;
+  [sFIRLoggerUserDefaults removeObjectForKey:kFIRPersistedDebugModeKey];
+  sFIRLoggerUserDefaults = nil;
+  GULResetLogger();
+}
+
+void FIRSetLoggerUserDefaults(NSUserDefaults *defaults) {
+  sFIRLoggerUserDefaults = defaults;
 }
+#endif
 
 /**
  * Check if the level is high enough to be loggable.
@@ -186,37 +123,11 @@ void FIRSetLoggerLevel(FIRLoggerLevel loggerLevel) {
 __attribute__((no_sanitize("thread"))) BOOL FIRIsLoggableLevel(FIRLoggerLevel loggerLevel,
                                                                BOOL analyticsComponent) {
   FIRLoggerInitializeASL();
-  if (sFIRLoggerDebugMode) {
-    return YES;
-  } else if (sFIRAnalyticsDebugMode && analyticsComponent) {
+  if (sFIRAnalyticsDebugMode && analyticsComponent) {
     return YES;
   }
-  return (BOOL)(loggerLevel <= sFIRLoggerMaximumLevel);
-}
-
-#ifdef DEBUG
-void FIRResetLogger() {
-  sFIRLoggerOnceToken = 0;
-  [sFIRLoggerUserDefaults removeObjectForKey:kFIRPersistedDebugModeKey];
-  sFIRLoggerUserDefaults = nil;
-}
-
-void FIRSetLoggerUserDefaults(NSUserDefaults *defaults) {
-  sFIRLoggerUserDefaults = defaults;
-}
-
-aslclient getFIRLoggerClient() {
-  return sFIRLoggerClient;
-}
-
-dispatch_queue_t getFIRClientQueue() {
-  return sFIRClientQueue;
-}
-
-BOOL getFIRLoggerDebugMode() {
-  return sFIRLoggerDebugMode;
+  return GULIsLoggableLevel((GULLoggerLevel)loggerLevel);
 }
-#endif
 
 void FIRLogBasic(FIRLoggerLevel level,
                  FIRLoggerService service,
@@ -224,32 +135,10 @@ void FIRLogBasic(FIRLoggerLevel level,
                  NSString *message,
                  va_list args_ptr) {
   FIRLoggerInitializeASL();
-  BOOL canLog = level <= sFIRLoggerMaximumLevel;
-
-  if (sFIRLoggerDebugMode) {
-    canLog = YES;
-  } else if (sFIRAnalyticsDebugMode && [kFIRLoggerAnalytics isEqualToString:service]) {
-    canLog = YES;
-  }
-
-  if (!canLog) {
-    return;
-  }
-#ifdef DEBUG
-  NSCAssert(messageCode.length == 11, @"Incorrect message code length.");
-  NSRange messageCodeRange = NSMakeRange(0, messageCode.length);
-  NSUInteger numberOfMatches =
-      [sMessageCodeRegex numberOfMatchesInString:messageCode options:0 range:messageCodeRange];
-  NSCAssert(numberOfMatches == 1, @"Incorrect message code format.");
-#endif
-  NSString *logMsg = [[NSString alloc] initWithFormat:message arguments:args_ptr];
-  logMsg =
-      [NSString stringWithFormat:@"%s - %@[%@] %@", FIRVersionString, service, messageCode, logMsg];
-  dispatch_async(sFIRClientQueue, ^{
-    asl_log(sFIRLoggerClient, NULL, level, "%s", logMsg.UTF8String);
-  });
+  GULLogBasic((GULLoggerLevel)level, service,
+              sFIRAnalyticsDebugMode && [kFIRLoggerAnalytics isEqualToString:service], messageCode,
+              message, args_ptr);
 }
-#pragma clang diagnostic pop
 
 /**
  * Generates the logging functions using macros.
diff --git a/Firebase/Core/FIRMutableDictionary.m b/Firebase/Core/FIRMutableDictionary.m
deleted file mode 100644
index 31941bc..0000000
--- a/Firebase/Core/FIRMutableDictionary.m
+++ /dev/null
@@ -1,97 +0,0 @@
-// Copyright 2017 Google
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#import "Private/FIRMutableDictionary.h"
-
-@implementation FIRMutableDictionary {
-  /// The mutable dictionary.
-  NSMutableDictionary *_objects;
-
-  /// Serial synchronization queue. All reads should use dispatch_sync, while writes use
-  /// dispatch_async.
-  dispatch_queue_t _queue;
-}
-
-- (instancetype)init {
-  self = [super init];
-
-  if (self) {
-    _objects = [[NSMutableDictionary alloc] init];
-    _queue = dispatch_queue_create("FIRMutableDictionary", DISPATCH_QUEUE_SERIAL);
-  }
-
-  return self;
-}
-
-- (NSString *)description {
-  __block NSString *description;
-  dispatch_sync(_queue, ^{
-    description = self->_objects.description;
-  });
-  return description;
-}
-
-- (id)objectForKey:(id)key {
-  __block id object;
-  dispatch_sync(_queue, ^{
-    object = self->_objects[key];
-  });
-  return object;
-}
-
-- (void)setObject:(id)object forKey:(id<NSCopying>)key {
-  dispatch_async(_queue, ^{
-    self->_objects[key] = object;
-  });
-}
-
-- (void)removeObjectForKey:(id)key {
-  dispatch_async(_queue, ^{
-    [self->_objects removeObjectForKey:key];
-  });
-}
-
-- (void)removeAllObjects {
-  dispatch_async(_queue, ^{
-    [self->_objects removeAllObjects];
-  });
-}
-
-- (NSUInteger)count {
-  __block NSUInteger count;
-  dispatch_sync(_queue, ^{
-    count = self->_objects.count;
-  });
-  return count;
-}
-
-- (id)objectForKeyedSubscript:(id<NSCopying>)key {
-  // The method this calls is already synchronized.
-  return [self objectForKey:key];
-}
-
-- (void)setObject:(id)obj forKeyedSubscript:(id<NSCopying>)key {
-  // The method this calls is already synchronized.
-  [self setObject:obj forKey:key];
-}
-
-- (NSDictionary *)dictionary {
-  __block NSDictionary *dictionary;
-  dispatch_sync(_queue, ^{
-    dictionary = [self->_objects copy];
-  });
-  return dictionary;
-}
-
-@end
diff --git a/Firebase/Core/FIRNetwork.m b/Firebase/Core/FIRNetwork.m
deleted file mode 100644
index ff292fc..0000000
--- a/Firebase/Core/FIRNetwork.m
+++ /dev/null
@@ -1,390 +0,0 @@
-// Copyright 2017 Google
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#import "Private/FIRNetwork.h"
-#import "Private/FIRNetworkMessageCode.h"
-
-#import "Private/FIRLogger.h"
-#import "Private/FIRMutableDictionary.h"
-#import "Private/FIRNetworkConstants.h"
-#import "Private/FIRReachabilityChecker.h"
-
-#import <GoogleToolboxForMac/GTMNSData+zlib.h>
-
-/// Constant string for request header Content-Encoding.
-static NSString *const kFIRNetworkContentCompressionKey = @"Content-Encoding";
-
-/// Constant string for request header Content-Encoding value.
-static NSString *const kFIRNetworkContentCompressionValue = @"gzip";
-
-/// Constant string for request header Content-Length.
-static NSString *const kFIRNetworkContentLengthKey = @"Content-Length";
-
-/// Constant string for request header Content-Type.
-static NSString *const kFIRNetworkContentTypeKey = @"Content-Type";
-
-/// Constant string for request header Content-Type value.
-static NSString *const kFIRNetworkContentTypeValue = @"application/x-www-form-urlencoded";
-
-/// Constant string for GET request method.
-static NSString *const kFIRNetworkGETRequestMethod = @"GET";
-
-/// Constant string for POST request method.
-static NSString *const kFIRNetworkPOSTRequestMethod = @"POST";
-
-/// Default constant string as a prefix for network logger.
-static NSString *const kFIRNetworkLogTag = @"Firebase/Network";
-
-@interface FIRNetwork () <FIRReachabilityDelegate, FIRNetworkLoggerDelegate>
-@end
-
-@implementation FIRNetwork {
-  /// Network reachability.
-  FIRReachabilityChecker *_reachability;
-
-  /// The dictionary of requests by session IDs { NSString : id }.
-  FIRMutableDictionary *_requests;
-}
-
-- (instancetype)init {
-  return [self initWithReachabilityHost:kFIRNetworkReachabilityHost];
-}
-
-- (instancetype)initWithReachabilityHost:(NSString *)reachabilityHost {
-  self = [super init];
-  if (self) {
-    // Setup reachability.
-    _reachability = [[FIRReachabilityChecker alloc] initWithReachabilityDelegate:self
-                                                                  loggerDelegate:self
-                                                                        withHost:reachabilityHost];
-    if (![_reachability start]) {
-      return nil;
-    }
-
-    _requests = [[FIRMutableDictionary alloc] init];
-    _timeoutInterval = kFIRNetworkTimeOutInterval;
-  }
-  return self;
-}
-
-- (void)dealloc {
-  _reachability.reachabilityDelegate = nil;
-  [_reachability stop];
-}
-
-#pragma mark - External Methods
-
-+ (void)handleEventsForBackgroundURLSessionID:(NSString *)sessionID
-                            completionHandler:(FIRNetworkSystemCompletionHandler)completionHandler {
-  [FIRNetworkURLSession handleEventsForBackgroundURLSessionID:sessionID
-                                            completionHandler:completionHandler];
-}
-
-- (NSString *)postURL:(NSURL *)url
-                   payload:(NSData *)payload
-                     queue:(dispatch_queue_t)queue
-    usingBackgroundSession:(BOOL)usingBackgroundSession
-         completionHandler:(FIRNetworkCompletionHandler)handler {
-  if (!url.absoluteString.length) {
-    [self handleErrorWithCode:FIRErrorCodeNetworkInvalidURL queue:queue withHandler:handler];
-    return nil;
-  }
-
-  NSTimeInterval timeOutInterval = _timeoutInterval ?: kFIRNetworkTimeOutInterval;
-
-  NSMutableURLRequest *request =
-      [[NSMutableURLRequest alloc] initWithURL:url
-                                   cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
-                               timeoutInterval:timeOutInterval];
-
-  if (!request) {
-    [self handleErrorWithCode:FIRErrorCodeNetworkSessionTaskCreation
-                        queue:queue
-                  withHandler:handler];
-    return nil;
-  }
-
-  NSError *compressError = nil;
-  NSData *compressedData = [NSData gtm_dataByGzippingData:payload error:&compressError];
-  if (!compressedData || compressError) {
-    if (compressError || payload.length > 0) {
-      // If the payload is not empty but it fails to compress the payload, something has been wrong.
-      [self handleErrorWithCode:FIRErrorCodeNetworkPayloadCompression
-                          queue:queue
-                    withHandler:handler];
-      return nil;
-    }
-    compressedData = [[NSData alloc] init];
-  }
-
-  NSString *postLength = @(compressedData.length).stringValue;
-
-  // Set up the request with the compressed data.
-  [request setValue:postLength forHTTPHeaderField:kFIRNetworkContentLengthKey];
-  request.HTTPBody = compressedData;
-  request.HTTPMethod = kFIRNetworkPOSTRequestMethod;
-  [request setValue:kFIRNetworkContentTypeValue forHTTPHeaderField:kFIRNetworkContentTypeKey];
-  [request setValue:kFIRNetworkContentCompressionValue
-      forHTTPHeaderField:kFIRNetworkContentCompressionKey];
-
-  FIRNetworkURLSession *fetcher = [[FIRNetworkURLSession alloc] initWithNetworkLoggerDelegate:self];
-  fetcher.backgroundNetworkEnabled = usingBackgroundSession;
-
-  __weak FIRNetwork *weakSelf = self;
-  NSString *requestID = [fetcher
-      sessionIDFromAsyncPOSTRequest:request
-                  completionHandler:^(NSHTTPURLResponse *response, NSData *data,
-                                      NSString *sessionID, NSError *error) {
-                    FIRNetwork *strongSelf = weakSelf;
-                    if (!strongSelf) {
-                      return;
-                    }
-                    dispatch_queue_t queueToDispatch = queue ? queue : dispatch_get_main_queue();
-                    dispatch_async(queueToDispatch, ^{
-                      if (sessionID.length) {
-                        [strongSelf->_requests removeObjectForKey:sessionID];
-                      }
-                      if (handler) {
-                        handler(response, data, error);
-                      }
-                    });
-                  }];
-  if (!requestID) {
-    [self handleErrorWithCode:FIRErrorCodeNetworkSessionTaskCreation
-                        queue:queue
-                  withHandler:handler];
-    return nil;
-  }
-
-  [self firNetwork_logWithLevel:kFIRNetworkLogLevelDebug
-                    messageCode:kFIRNetworkMessageCodeNetwork000
-                        message:@"Uploading data. Host"
-                        context:url];
-  _requests[requestID] = fetcher;
-  return requestID;
-}
-
-- (NSString *)getURL:(NSURL *)url
-                   headers:(NSDictionary *)headers
-                     queue:(dispatch_queue_t)queue
-    usingBackgroundSession:(BOOL)usingBackgroundSession
-         completionHandler:(FIRNetworkCompletionHandler)handler {
-  if (!url.absoluteString.length) {
-    [self handleErrorWithCode:FIRErrorCodeNetworkInvalidURL queue:queue withHandler:handler];
-    return nil;
-  }
-
-  NSTimeInterval timeOutInterval = _timeoutInterval ?: kFIRNetworkTimeOutInterval;
-  NSMutableURLRequest *request =
-      [[NSMutableURLRequest alloc] initWithURL:url
-                                   cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
-                               timeoutInterval:timeOutInterval];
-
-  if (!request) {
-    [self handleErrorWithCode:FIRErrorCodeNetworkSessionTaskCreation
-                        queue:queue
-                  withHandler:handler];
-    return nil;
-  }
-
-  request.HTTPMethod = kFIRNetworkGETRequestMethod;
-  request.allHTTPHeaderFields = headers;
-
-  FIRNetworkURLSession *fetcher = [[FIRNetworkURLSession alloc] initWithNetworkLoggerDelegate:self];
-  fetcher.backgroundNetworkEnabled = usingBackgroundSession;
-
-  __weak FIRNetwork *weakSelf = self;
-  NSString *requestID = [fetcher
-      sessionIDFromAsyncGETRequest:request
-                 completionHandler:^(NSHTTPURLResponse *response, NSData *data, NSString *sessionID,
-                                     NSError *error) {
-                   FIRNetwork *strongSelf = weakSelf;
-                   if (!strongSelf) {
-                     return;
-                   }
-                   dispatch_queue_t queueToDispatch = queue ? queue : dispatch_get_main_queue();
-                   dispatch_async(queueToDispatch, ^{
-                     if (sessionID.length) {
-                       [strongSelf->_requests removeObjectForKey:sessionID];
-                     }
-                     if (handler) {
-                       handler(response, data, error);
-                     }
-                   });
-                 }];
-
-  if (!requestID) {
-    [self handleErrorWithCode:FIRErrorCodeNetworkSessionTaskCreation
-                        queue:queue
-                  withHandler:handler];
-    return nil;
-  }
-
-  [self firNetwork_logWithLevel:kFIRNetworkLogLevelDebug
-                    messageCode:kFIRNetworkMessageCodeNetwork001
-                        message:@"Downloading data. Host"
-                        context:url];
-  _requests[requestID] = fetcher;
-  return requestID;
-}
-
-- (BOOL)hasUploadInProgress {
-  return _requests.count > 0;
-}
-
-#pragma mark - Network Reachability
-
-/// Tells reachability delegate to call reachabilityDidChangeToStatus: to notify the network
-/// reachability has changed.
-- (void)reachability:(FIRReachabilityChecker *)reachability
-       statusChanged:(FIRReachabilityStatus)status {
-  _networkConnected = (status == kFIRReachabilityViaCellular || status == kFIRReachabilityViaWifi);
-  [_reachabilityDelegate reachabilityDidChange];
-}
-
-#pragma mark - Network logger delegate
-
-- (void)setLoggerDelegate:(id<FIRNetworkLoggerDelegate>)loggerDelegate {
-  // Explicitly check whether the delegate responds to the methods because conformsToProtocol does
-  // not work correctly even though the delegate does respond to the methods.
-  if (!loggerDelegate ||
-      ![loggerDelegate
-          respondsToSelector:@selector(firNetwork_logWithLevel:messageCode:message:contexts:)] ||
-      ![loggerDelegate
-          respondsToSelector:@selector(firNetwork_logWithLevel:messageCode:message:context:)] ||
-      !
-      [loggerDelegate respondsToSelector:@selector(firNetwork_logWithLevel:messageCode:message:)]) {
-    FIRLogError(kFIRLoggerAnalytics,
-                [NSString stringWithFormat:@"I-NET%06ld", (long)kFIRNetworkMessageCodeNetwork002],
-                @"Cannot set the network logger delegate: delegate does not conform to the network "
-                 "logger protocol.");
-    return;
-  }
-  _loggerDelegate = loggerDelegate;
-}
-
-#pragma mark - Private methods
-
-/// Handles network error and calls completion handler with the error.
-- (void)handleErrorWithCode:(NSInteger)code
-                      queue:(dispatch_queue_t)queue
-                withHandler:(FIRNetworkCompletionHandler)handler {
-  NSDictionary *userInfo = @{kFIRNetworkErrorContext : @"Failed to create network request"};
-  NSError *error =
-      [[NSError alloc] initWithDomain:kFIRNetworkErrorDomain code:code userInfo:userInfo];
-  [self firNetwork_logWithLevel:kFIRNetworkLogLevelWarning
-                    messageCode:kFIRNetworkMessageCodeNetwork002
-                        message:@"Failed to create network request. Code, error"
-                       contexts:@[ @(code), error ]];
-  if (handler) {
-    dispatch_queue_t queueToDispatch = queue ? queue : dispatch_get_main_queue();
-    dispatch_async(queueToDispatch, ^{
-      handler(nil, nil, error);
-    });
-  }
-}
-
-#pragma mark - Network logger
-
-- (void)firNetwork_logWithLevel:(FIRNetworkLogLevel)logLevel
-                    messageCode:(FIRNetworkMessageCode)messageCode
-                        message:(NSString *)message
-                       contexts:(NSArray *)contexts {
-  // Let the delegate log the message if there is a valid logger delegate. Otherwise, just log
-  // errors/warnings/info messages to the console log.
-  if (_loggerDelegate) {
-    [_loggerDelegate firNetwork_logWithLevel:logLevel
-                                 messageCode:messageCode
-                                     message:message
-                                    contexts:contexts];
-    return;
-  }
-  if (_isDebugModeEnabled || logLevel == kFIRNetworkLogLevelError ||
-      logLevel == kFIRNetworkLogLevelWarning || logLevel == kFIRNetworkLogLevelInfo) {
-    NSString *formattedMessage = FIRStringWithLogMessage(message, logLevel, contexts);
-    NSLog(@"%@", formattedMessage);
-    FIRLogBasic((FIRLoggerLevel)logLevel, kFIRLoggerCore,
-                [NSString stringWithFormat:@"I-NET%06ld", (long)messageCode], formattedMessage,
-                NULL);
-  }
-}
-
-- (void)firNetwork_logWithLevel:(FIRNetworkLogLevel)logLevel
-                    messageCode:(FIRNetworkMessageCode)messageCode
-                        message:(NSString *)message
-                        context:(id)context {
-  if (_loggerDelegate) {
-    [_loggerDelegate firNetwork_logWithLevel:logLevel
-                                 messageCode:messageCode
-                                     message:message
-                                     context:context];
-    return;
-  }
-  NSArray *contexts = context ? @[ context ] : @[];
-  [self firNetwork_logWithLevel:logLevel messageCode:messageCode message:message contexts:contexts];
-}
-
-- (void)firNetwork_logWithLevel:(FIRNetworkLogLevel)logLevel
-                    messageCode:(FIRNetworkMessageCode)messageCode
-                        message:(NSString *)message {
-  if (_loggerDelegate) {
-    [_loggerDelegate firNetwork_logWithLevel:logLevel messageCode:messageCode message:message];
-    return;
-  }
-  [self firNetwork_logWithLevel:logLevel messageCode:messageCode message:message contexts:@[]];
-}
-
-/// Returns a string for the given log level (e.g. kFIRNetworkLogLevelError -> @"ERROR").
-static NSString *FIRLogLevelDescriptionFromLogLevel(FIRNetworkLogLevel logLevel) {
-  static NSDictionary *levelNames = nil;
-  static dispatch_once_t onceToken;
-  dispatch_once(&onceToken, ^{
-    levelNames = @{
-      @(kFIRNetworkLogLevelError) : @"ERROR",
-      @(kFIRNetworkLogLevelWarning) : @"WARNING",
-      @(kFIRNetworkLogLevelInfo) : @"INFO",
-      @(kFIRNetworkLogLevelDebug) : @"DEBUG"
-    };
-  });
-  return levelNames[@(logLevel)];
-}
-
-/// Returns a formatted string to be used for console logging.
-static NSString *FIRStringWithLogMessage(NSString *message,
-                                         FIRNetworkLogLevel logLevel,
-                                         NSArray *contexts) {
-  if (!message) {
-    message = @"(Message was nil)";
-  } else if (!message.length) {
-    message = @"(Message was empty)";
-  }
-  NSMutableString *result = [[NSMutableString alloc]
-      initWithFormat:@"<%@/%@> %@", kFIRNetworkLogTag, FIRLogLevelDescriptionFromLogLevel(logLevel),
-                     message];
-
-  if (!contexts.count) {
-    return result;
-  }
-
-  NSMutableArray *formattedContexts = [[NSMutableArray alloc] init];
-  for (id item in contexts) {
-    [formattedContexts addObject:(item != [NSNull null] ? item : @"(nil)")];
-  }
-
-  [result appendString:@": "];
-  [result appendString:[formattedContexts componentsJoinedByString:@", "]];
-  return result;
-}
-
-@end
diff --git a/Firebase/Core/FIRNetworkConstants.m b/Firebase/Core/FIRNetworkConstants.m
deleted file mode 100644
index c958201..0000000
--- a/Firebase/Core/FIRNetworkConstants.m
+++ /dev/null
@@ -1,39 +0,0 @@
-// Copyright 2017 Google
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#import "Private/FIRNetworkConstants.h"
-
-#import <Foundation/Foundation.h>
-
-NSString *const kFIRNetworkBackgroundSessionConfigIDPrefix =
-    @"com.firebase.network.background-upload";
-NSString *const kFIRNetworkApplicationSupportSubdirectory = @"Firebase/Network";
-NSString *const kFIRNetworkTempDirectoryName = @"FIRNetworkTemporaryDirectory";
-const NSTimeInterval kFIRNetworkTempFolderExpireTime = 60 * 60;  // 1 hour
-const NSTimeInterval kFIRNetworkTimeOutInterval = 60;            // 1 minute.
-NSString *const kFIRNetworkReachabilityHost = @"app-measurement.com";
-NSString *const kFIRNetworkErrorContext = @"Context";
-
-const int kFIRNetworkHTTPStatusOK = 200;
-const int kFIRNetworkHTTPStatusNoContent = 204;
-const int kFIRNetworkHTTPStatusCodeMultipleChoices = 300;
-const int kFIRNetworkHTTPStatusCodeMovedPermanently = 301;
-const int kFIRNetworkHTTPStatusCodeFound = 302;
-const int kFIRNetworkHTTPStatusCodeNotModified = 304;
-const int kFIRNetworkHTTPStatusCodeMovedTemporarily = 307;
-const int kFIRNetworkHTTPStatusCodeNotFound = 404;
-const int kFIRNetworkHTTPStatusCodeCannotAcceptTraffic = 429;
-const int kFIRNetworkHTTPStatusCodeUnavailable = 503;
-
-NSString *const kFIRNetworkErrorDomain = @"com.firebase.network.ErrorDomain";
diff --git a/Firebase/Core/FIRNetworkURLSession.m b/Firebase/Core/FIRNetworkURLSession.m
deleted file mode 100644
index 470d3e9..0000000
--- a/Firebase/Core/FIRNetworkURLSession.m
+++ /dev/null
@@ -1,669 +0,0 @@
-// Copyright 2017 Google
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#import <Foundation/Foundation.h>
-
-#import "Private/FIRNetworkURLSession.h"
-
-#import "Private/FIRLogger.h"
-#import "Private/FIRMutableDictionary.h"
-#import "Private/FIRNetworkConstants.h"
-#import "Private/FIRNetworkMessageCode.h"
-
-@implementation FIRNetworkURLSession {
-  /// The handler to be called when the request completes or error has occurs.
-  FIRNetworkURLSessionCompletionHandler _completionHandler;
-
-  /// Session ID generated randomly with a fixed prefix.
-  NSString *_sessionID;
-
-  /// The session configuration.
-  NSURLSessionConfiguration *_sessionConfig;
-
-  /// The path to the directory where all temporary files are stored before uploading.
-  NSURL *_networkDirectoryURL;
-
-  /// The downloaded data from fetching.
-  NSData *_downloadedData;
-
-  /// The path to the temporary file which stores the uploading data.
-  NSURL *_uploadingFileURL;
-
-  /// The current request.
-  NSURLRequest *_request;
-}
-
-#pragma mark - Init
-
-- (instancetype)initWithNetworkLoggerDelegate:(id<FIRNetworkLoggerDelegate>)networkLoggerDelegate {
-  self = [super init];
-  if (self) {
-    // Create URL to the directory where all temporary files to upload have to be stored.
-    NSArray *paths =
-        NSSearchPathForDirectoriesInDomains(NSApplicationSupportDirectory, NSUserDomainMask, YES);
-    NSString *applicationSupportDirectory = paths.firstObject;
-    NSArray *tempPathComponents = @[
-      applicationSupportDirectory, kFIRNetworkApplicationSupportSubdirectory,
-      kFIRNetworkTempDirectoryName
-    ];
-    _networkDirectoryURL = [NSURL fileURLWithPathComponents:tempPathComponents];
-    _sessionID = [NSString stringWithFormat:@"%@-%@", kFIRNetworkBackgroundSessionConfigIDPrefix,
-                                            [[NSUUID UUID] UUIDString]];
-    _loggerDelegate = networkLoggerDelegate;
-  }
-  return self;
-}
-
-#pragma mark - External Methods
-
-#pragma mark - To be called from AppDelegate
-
-+ (void)handleEventsForBackgroundURLSessionID:(NSString *)sessionID
-                            completionHandler:
-                                (FIRNetworkSystemCompletionHandler)systemCompletionHandler {
-  // The session may not be FIRAnalytics background. Ignore those that do not have the prefix.
-  if (![sessionID hasPrefix:kFIRNetworkBackgroundSessionConfigIDPrefix]) {
-    return;
-  }
-  FIRNetworkURLSession *fetcher = [self fetcherWithSessionIdentifier:sessionID];
-  if (fetcher != nil) {
-    [fetcher addSystemCompletionHandler:systemCompletionHandler forSession:sessionID];
-  } else {
-    FIRLogError(kFIRLoggerCore,
-                [NSString stringWithFormat:@"I-NET%06ld", (long)kFIRNetworkMessageCodeNetwork003],
-                @"Failed to retrieve background session with ID %@ after app is relaunched.",
-                sessionID);
-  }
-}
-
-#pragma mark - External Methods
-
-/// Sends an async POST request using NSURLSession for iOS >= 7.0, and returns an ID of the
-/// connection.
-- (NSString *)sessionIDFromAsyncPOSTRequest:(NSURLRequest *)request
-                          completionHandler:(FIRNetworkURLSessionCompletionHandler)handler {
-  // NSURLSessionUploadTask does not work with NSData in the background.
-  // To avoid this issue, write the data to a temporary file to upload it.
-  // Make a temporary file with the data subset.
-  _uploadingFileURL = [self temporaryFilePathWithSessionID:_sessionID];
-  NSError *writeError;
-  NSURLSessionUploadTask *postRequestTask;
-  NSURLSession *session;
-  BOOL didWriteFile = NO;
-
-  // Clean up the entire temp folder to avoid temp files that remain in case the previous session
-  // crashed and did not clean up.
-  [self maybeRemoveTempFilesAtURL:_networkDirectoryURL
-                     expiringTime:kFIRNetworkTempFolderExpireTime];
-
-  // If there is no background network enabled, no need to write to file. This will allow default
-  // network session which runs on the foreground.
-  if (_backgroundNetworkEnabled && [self ensureTemporaryDirectoryExists]) {
-    didWriteFile = [request.HTTPBody writeToFile:_uploadingFileURL.path
-                                         options:NSDataWritingAtomic
-                                           error:&writeError];
-
-    if (writeError) {
-      [_loggerDelegate firNetwork_logWithLevel:kFIRNetworkLogLevelError
-                                   messageCode:kFIRNetworkMessageCodeURLSession000
-                                       message:@"Failed to write request data to file"
-                                       context:writeError];
-    }
-  }
-
-  if (didWriteFile) {
-    // Exclude this file from backing up to iTunes. There are conflicting reports that excluding
-    // directory from backing up does not excluding files of that directory from backing up.
-    [self excludeFromBackupForURL:_uploadingFileURL];
-
-    _sessionConfig = [self backgroundSessionConfigWithSessionID:_sessionID];
-    [self populateSessionConfig:_sessionConfig withRequest:request];
-    session = [NSURLSession sessionWithConfiguration:_sessionConfig
-                                            delegate:self
-                                       delegateQueue:[NSOperationQueue mainQueue]];
-    postRequestTask = [session uploadTaskWithRequest:request fromFile:_uploadingFileURL];
-  } else {
-    // If we cannot write to file, just send it in the foreground.
-    _sessionConfig = [NSURLSessionConfiguration defaultSessionConfiguration];
-    [self populateSessionConfig:_sessionConfig withRequest:request];
-    _sessionConfig.URLCache = nil;
-    session = [NSURLSession sessionWithConfiguration:_sessionConfig
-                                            delegate:self
-                                       delegateQueue:[NSOperationQueue mainQueue]];
-    postRequestTask = [session uploadTaskWithRequest:request fromData:request.HTTPBody];
-  }
-
-  if (!session || !postRequestTask) {
-    NSError *error = [[NSError alloc]
-        initWithDomain:kFIRNetworkErrorDomain
-                  code:FIRErrorCodeNetworkRequestCreation
-              userInfo:@{kFIRNetworkErrorContext : @"Cannot create network session"}];
-    [self callCompletionHandler:handler withResponse:nil data:nil error:error];
-    return nil;
-  }
-
-  // Save the session into memory.
-  NSMapTable *sessionIdentifierToFetcherMap = [[self class] sessionIDToFetcherMap];
-  [sessionIdentifierToFetcherMap setObject:self forKey:_sessionID];
-
-  _request = [request copy];
-
-  // Store completion handler because background session does not accept handler block but custom
-  // delegate.
-  _completionHandler = [handler copy];
-  [postRequestTask resume];
-
-  return _sessionID;
-}
-
-/// Sends an async GET request using NSURLSession for iOS >= 7.0, and returns an ID of the session.
-- (NSString *)sessionIDFromAsyncGETRequest:(NSURLRequest *)request
-                         completionHandler:(FIRNetworkURLSessionCompletionHandler)handler {
-  if (_backgroundNetworkEnabled) {
-    _sessionConfig = [self backgroundSessionConfigWithSessionID:_sessionID];
-  } else {
-    _sessionConfig = [NSURLSessionConfiguration defaultSessionConfiguration];
-  }
-
-  [self populateSessionConfig:_sessionConfig withRequest:request];
-
-  // Do not cache the GET request.
-  _sessionConfig.URLCache = nil;
-
-  NSURLSession *session = [NSURLSession sessionWithConfiguration:_sessionConfig
-                                                        delegate:self
-                                                   delegateQueue:[NSOperationQueue mainQueue]];
-  NSURLSessionDownloadTask *downloadTask = [session downloadTaskWithRequest:request];
-
-  if (!session || !downloadTask) {
-    NSError *error = [[NSError alloc]
-        initWithDomain:kFIRNetworkErrorDomain
-                  code:FIRErrorCodeNetworkRequestCreation
-              userInfo:@{kFIRNetworkErrorContext : @"Cannot create network session"}];
-    [self callCompletionHandler:handler withResponse:nil data:nil error:error];
-    return nil;
-  }
-
-  // Save the session into memory.
-  NSMapTable *sessionIdentifierToFetcherMap = [[self class] sessionIDToFetcherMap];
-  [sessionIdentifierToFetcherMap setObject:self forKey:_sessionID];
-
-  _request = [request copy];
-
-  _completionHandler = [handler copy];
-  [downloadTask resume];
-
-  return _sessionID;
-}
-
-#pragma mark - NSURLSessionTaskDelegate
-
-/// Called by the NSURLSession once the download task is completed. The file is saved in the
-/// provided URL so we need to read the data and store into _downloadedData. Once the session is
-/// completed, URLSession:task:didCompleteWithError will be called and the completion handler will
-/// be called with the downloaded data.
-- (void)URLSession:(NSURLSession *)session
-                 downloadTask:(NSURLSessionDownloadTask *)task
-    didFinishDownloadingToURL:(NSURL *)url {
-  if (!url.path) {
-    [_loggerDelegate
-        firNetwork_logWithLevel:kFIRNetworkLogLevelError
-                    messageCode:kFIRNetworkMessageCodeURLSession001
-                        message:@"Unable to read downloaded data from empty temp path"];
-    _downloadedData = nil;
-    return;
-  }
-
-  NSError *error;
-  _downloadedData = [NSData dataWithContentsOfFile:url.path options:0 error:&error];
-
-  if (error) {
-    [_loggerDelegate firNetwork_logWithLevel:kFIRNetworkLogLevelError
-                                 messageCode:kFIRNetworkMessageCodeURLSession002
-                                     message:@"Cannot read the content of downloaded data"
-                                     context:error];
-    _downloadedData = nil;
-  }
-}
-
-#if TARGET_OS_IOS || TARGET_OS_TV
-- (void)URLSessionDidFinishEventsForBackgroundURLSession:(NSURLSession *)session {
-  [_loggerDelegate firNetwork_logWithLevel:kFIRNetworkLogLevelDebug
-                               messageCode:kFIRNetworkMessageCodeURLSession003
-                                   message:@"Background session finished"
-                                   context:session.configuration.identifier];
-  [self callSystemCompletionHandler:session.configuration.identifier];
-}
-#endif
-
-- (void)URLSession:(NSURLSession *)session
-                    task:(NSURLSessionTask *)task
-    didCompleteWithError:(NSError *)error {
-  // Avoid any chance of recursive behavior leading to it being used repeatedly.
-  FIRNetworkURLSessionCompletionHandler handler = _completionHandler;
-  _completionHandler = nil;
-
-  if (task.response) {
-    // The following assertion should always be true for HTTP requests, see https://goo.gl/gVLxT7.
-    NSAssert([task.response isKindOfClass:[NSHTTPURLResponse class]], @"URL response must be HTTP");
-
-    // The server responded so ignore the error created by the system.
-    error = nil;
-  } else if (!error) {
-    error = [[NSError alloc]
-        initWithDomain:kFIRNetworkErrorDomain
-                  code:FIRErrorCodeNetworkInvalidResponse
-              userInfo:@{kFIRNetworkErrorContext : @"Network Error: Empty network response"}];
-  }
-
-  [self callCompletionHandler:handler
-                 withResponse:(NSHTTPURLResponse *)task.response
-                         data:_downloadedData
-                        error:error];
-
-  // Remove the temp file to avoid trashing devices with lots of temp files.
-  [self removeTempItemAtURL:_uploadingFileURL];
-
-  // Try to clean up stale files again.
-  [self maybeRemoveTempFilesAtURL:_networkDirectoryURL
-                     expiringTime:kFIRNetworkTempFolderExpireTime];
-}
-
-- (void)URLSession:(NSURLSession *)session
-                   task:(NSURLSessionTask *)task
-    didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge
-      completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition disposition,
-                                  NSURLCredential *credential))completionHandler {
-  // The handling is modeled after GTMSessionFetcher.
-  if ([challenge.protectionSpace.authenticationMethod
-          isEqualToString:NSURLAuthenticationMethodServerTrust]) {
-    SecTrustRef serverTrust = challenge.protectionSpace.serverTrust;
-    if (serverTrust == NULL) {
-      [_loggerDelegate firNetwork_logWithLevel:kFIRNetworkLogLevelDebug
-                                   messageCode:kFIRNetworkMessageCodeURLSession004
-                                       message:@"Received empty server trust for host. Host"
-                                       context:_request.URL];
-      completionHandler(NSURLSessionAuthChallengePerformDefaultHandling, nil);
-      return;
-    }
-    NSURLCredential *credential = [NSURLCredential credentialForTrust:serverTrust];
-    if (!credential) {
-      [_loggerDelegate firNetwork_logWithLevel:kFIRNetworkLogLevelWarning
-                                   messageCode:kFIRNetworkMessageCodeURLSession005
-                                       message:@"Unable to verify server identity. Host"
-                                       context:_request.URL];
-      completionHandler(NSURLSessionAuthChallengeCancelAuthenticationChallenge, nil);
-      return;
-    }
-
-    [_loggerDelegate firNetwork_logWithLevel:kFIRNetworkLogLevelDebug
-                                 messageCode:kFIRNetworkMessageCodeURLSession006
-                                     message:@"Received SSL challenge for host. Host"
-                                     context:_request.URL];
-
-    void (^callback)(BOOL) = ^(BOOL allow) {
-      if (allow) {
-        completionHandler(NSURLSessionAuthChallengeUseCredential, credential);
-      } else {
-        [self->_loggerDelegate
-            firNetwork_logWithLevel:kFIRNetworkLogLevelDebug
-                        messageCode:kFIRNetworkMessageCodeURLSession007
-                            message:@"Cancelling authentication challenge for host. Host"
-                            context:self->_request.URL];
-        completionHandler(NSURLSessionAuthChallengeCancelAuthenticationChallenge, nil);
-      }
-    };
-
-    // Retain the trust object to avoid a SecTrustEvaluate() crash on iOS 7.
-    CFRetain(serverTrust);
-
-    // Evaluate the certificate chain.
-    //
-    // The delegate queue may be the main thread. Trust evaluation could cause some
-    // blocking network activity, so we must evaluate async, as documented at
-    // https://developer.apple.com/library/ios/technotes/tn2232/
-    dispatch_queue_t evaluateBackgroundQueue =
-        dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
-
-    dispatch_async(evaluateBackgroundQueue, ^{
-      SecTrustResultType trustEval = kSecTrustResultInvalid;
-      BOOL shouldAllow;
-      OSStatus trustError;
-
-      @synchronized([FIRNetworkURLSession class]) {
-        trustError = SecTrustEvaluate(serverTrust, &trustEval);
-      }
-
-      if (trustError != errSecSuccess) {
-        [self->_loggerDelegate firNetwork_logWithLevel:kFIRNetworkLogLevelError
-                                           messageCode:kFIRNetworkMessageCodeURLSession008
-                                               message:@"Cannot evaluate server trust. Error, host"
-                                              contexts:@[ @(trustError), self->_request.URL ]];
-        shouldAllow = NO;
-      } else {
-        // Having a trust level "unspecified" by the user is the usual result, described at
-        // https://developer.apple.com/library/mac/qa/qa1360
-        shouldAllow =
-            (trustEval == kSecTrustResultUnspecified || trustEval == kSecTrustResultProceed);
-      }
-
-      // Call the call back with the permission.
-      callback(shouldAllow);
-
-      CFRelease(serverTrust);
-    });
-    return;
-  }
-
-  // Default handling for other Auth Challenges.
-  completionHandler(NSURLSessionAuthChallengePerformDefaultHandling, nil);
-}
-
-#pragma mark - Internal Methods
-
-/// Stores system completion handler with session ID as key.
-- (void)addSystemCompletionHandler:(FIRNetworkSystemCompletionHandler)handler
-                        forSession:(NSString *)identifier {
-  if (!handler) {
-    [_loggerDelegate
-        firNetwork_logWithLevel:kFIRNetworkLogLevelError
-                    messageCode:kFIRNetworkMessageCodeURLSession009
-                        message:@"Cannot store nil system completion handler in network"];
-    return;
-  }
-
-  if (!identifier.length) {
-    [_loggerDelegate
-        firNetwork_logWithLevel:kFIRNetworkLogLevelError
-                    messageCode:kFIRNetworkMessageCodeURLSession010
-                        message:
-                            @"Cannot store system completion handler with empty network "
-                             "session identifier"];
-    return;
-  }
-
-  FIRMutableDictionary *systemCompletionHandlers =
-      [[self class] sessionIDToSystemCompletionHandlerDictionary];
-  if (systemCompletionHandlers[identifier]) {
-    [_loggerDelegate firNetwork_logWithLevel:kFIRNetworkLogLevelWarning
-                                 messageCode:kFIRNetworkMessageCodeURLSession011
-                                     message:@"Got multiple system handlers for a single session ID"
-                                     context:identifier];
-  }
-
-  systemCompletionHandlers[identifier] = handler;
-}
-
-/// Calls the system provided completion handler with the session ID stored in the dictionary.
-/// The handler will be removed from the dictionary after being called.
-- (void)callSystemCompletionHandler:(NSString *)identifier {
-  FIRMutableDictionary *systemCompletionHandlers =
-      [[self class] sessionIDToSystemCompletionHandlerDictionary];
-  FIRNetworkSystemCompletionHandler handler = [systemCompletionHandlers objectForKey:identifier];
-
-  if (handler) {
-    [systemCompletionHandlers removeObjectForKey:identifier];
-
-    dispatch_async(dispatch_get_main_queue(), ^{
-      handler();
-    });
-  }
-}
-
-/// Sets or updates the session ID of this session.
-- (void)setSessionID:(NSString *)sessionID {
-  _sessionID = [sessionID copy];
-}
-
-/// Creates a background session configuration with the session ID using the supported method.
-- (NSURLSessionConfiguration *)backgroundSessionConfigWithSessionID:(NSString *)sessionID {
-#if (TARGET_OS_OSX && defined(MAC_OS_X_VERSION_10_10) &&         \
-     MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_10) || \
-    TARGET_OS_TV ||                                              \
-    (TARGET_OS_IOS && defined(__IPHONE_8_0) && __IPHONE_OS_VERSION_MIN_REQUIRED >= __IPHONE_8_0)
-
-  // iOS 8/10.10 builds require the new backgroundSessionConfiguration method name.
-  return [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:sessionID];
-
-#elif (TARGET_OS_OSX && defined(MAC_OS_X_VERSION_10_10) &&        \
-       MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_10) || \
-    (TARGET_OS_IOS && defined(__IPHONE_8_0) && __IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_8_0)
-
-  // Do a runtime check to avoid a deprecation warning about using
-  // +backgroundSessionConfiguration: on iOS 8.
-  if ([NSURLSessionConfiguration
-          respondsToSelector:@selector(backgroundSessionConfigurationWithIdentifier:)]) {
-    // Running on iOS 8+/OS X 10.10+.
-    return [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:sessionID];
-  } else {
-    // Running on iOS 7/OS X 10.9.
-    return [NSURLSessionConfiguration backgroundSessionConfiguration:sessionID];
-  }
-
-#else
-  // Building with an SDK earlier than iOS 8/OS X 10.10.
-  return [NSURLSessionConfiguration backgroundSessionConfiguration:sessionID];
-#endif
-}
-
-- (void)maybeRemoveTempFilesAtURL:(NSURL *)folderURL expiringTime:(NSTimeInterval)staleTime {
-  if (!folderURL.absoluteString.length) {
-    return;
-  }
-
-  NSFileManager *fileManager = [NSFileManager defaultManager];
-  NSError *error = nil;
-
-  NSArray *properties = @[ NSURLCreationDateKey ];
-  NSArray *directoryContent =
-      [fileManager contentsOfDirectoryAtURL:folderURL
-                 includingPropertiesForKeys:properties
-                                    options:NSDirectoryEnumerationSkipsSubdirectoryDescendants
-                                      error:&error];
-  if (error && error.code != NSFileReadNoSuchFileError) {
-    [_loggerDelegate
-        firNetwork_logWithLevel:kFIRNetworkLogLevelDebug
-                    messageCode:kFIRNetworkMessageCodeURLSession012
-                        message:@"Cannot get files from the temporary network folder. Error"
-                        context:error];
-    return;
-  }
-
-  if (!directoryContent.count) {
-    return;
-  }
-
-  NSTimeInterval now = [NSDate date].timeIntervalSince1970;
-  for (NSURL *tempFile in directoryContent) {
-    NSDate *creationDate;
-    BOOL getCreationDate =
-        [tempFile getResourceValue:&creationDate forKey:NSURLCreationDateKey error:NULL];
-    if (!getCreationDate) {
-      continue;
-    }
-    NSTimeInterval creationTimeInterval = creationDate.timeIntervalSince1970;
-    if (fabs(now - creationTimeInterval) > staleTime) {
-      [self removeTempItemAtURL:tempFile];
-    }
-  }
-}
-
-/// Removes the temporary file written to disk for sending the request. It has to be cleaned up
-/// after the session is done.
-- (void)removeTempItemAtURL:(NSURL *)fileURL {
-  if (!fileURL.absoluteString.length) {
-    return;
-  }
-
-  NSFileManager *fileManager = [NSFileManager defaultManager];
-  NSError *error = nil;
-
-  if (![fileManager removeItemAtURL:fileURL error:&error] && error.code != NSFileNoSuchFileError) {
-    [_loggerDelegate
-        firNetwork_logWithLevel:kFIRNetworkLogLevelError
-                    messageCode:kFIRNetworkMessageCodeURLSession013
-                        message:@"Failed to remove temporary uploading data file. Error"
-                        context:error.localizedDescription];
-  }
-}
-
-/// Gets the fetcher with the session ID.
-+ (instancetype)fetcherWithSessionIdentifier:(NSString *)sessionIdentifier {
-  NSMapTable *sessionIdentifierToFetcherMap = [self sessionIDToFetcherMap];
-  FIRNetworkURLSession *session = [sessionIdentifierToFetcherMap objectForKey:sessionIdentifier];
-  if (!session && [sessionIdentifier hasPrefix:kFIRNetworkBackgroundSessionConfigIDPrefix]) {
-    session = [[FIRNetworkURLSession alloc] initWithNetworkLoggerDelegate:nil];
-    [session setSessionID:sessionIdentifier];
-    [sessionIdentifierToFetcherMap setObject:session forKey:sessionIdentifier];
-  }
-  return session;
-}
-
-/// Returns a map of the fetcher by session ID. Creates a map if it is not created.
-+ (NSMapTable *)sessionIDToFetcherMap {
-  static NSMapTable *sessionIDToFetcherMap;
-
-  static dispatch_once_t sessionMapOnceToken;
-  dispatch_once(&sessionMapOnceToken, ^{
-    sessionIDToFetcherMap = [NSMapTable strongToWeakObjectsMapTable];
-  });
-  return sessionIDToFetcherMap;
-}
-
-/// Returns a map of system provided completion handler by session ID. Creates a map if it is not
-/// created.
-+ (FIRMutableDictionary *)sessionIDToSystemCompletionHandlerDictionary {
-  static FIRMutableDictionary *systemCompletionHandlers;
-
-  static dispatch_once_t systemCompletionHandlerOnceToken;
-  dispatch_once(&systemCompletionHandlerOnceToken, ^{
-    systemCompletionHandlers = [[FIRMutableDictionary alloc] init];
-  });
-  return systemCompletionHandlers;
-}
-
-- (NSURL *)temporaryFilePathWithSessionID:(NSString *)sessionID {
-  NSString *tempName = [NSString stringWithFormat:@"FIRUpload_temp_%@", sessionID];
-  return [_networkDirectoryURL URLByAppendingPathComponent:tempName];
-}
-
-/// Makes sure that the directory to store temp files exists. If not, tries to create it and returns
-/// YES. If there is anything wrong, returns NO.
-- (BOOL)ensureTemporaryDirectoryExists {
-  NSFileManager *fileManager = [NSFileManager defaultManager];
-  NSError *error = nil;
-
-  // Create a temporary directory if it does not exist or was deleted.
-  if ([_networkDirectoryURL checkResourceIsReachableAndReturnError:&error]) {
-    return YES;
-  }
-
-  if (error && error.code != NSFileReadNoSuchFileError) {
-    [_loggerDelegate
-        firNetwork_logWithLevel:kFIRNetworkLogLevelWarning
-                    messageCode:kFIRNetworkMessageCodeURLSession014
-                        message:@"Error while trying to access Network temp folder. Error"
-                        context:error];
-  }
-
-  NSError *writeError = nil;
-
-  [fileManager createDirectoryAtURL:_networkDirectoryURL
-        withIntermediateDirectories:YES
-                         attributes:nil
-                              error:&writeError];
-  if (writeError) {
-    [_loggerDelegate firNetwork_logWithLevel:kFIRNetworkLogLevelError
-                                 messageCode:kFIRNetworkMessageCodeURLSession015
-                                     message:@"Cannot create temporary directory. Error"
-                                     context:writeError];
-    return NO;
-  }
-
-  // Set the iCloud exclusion attribute on the Documents URL.
-  [self excludeFromBackupForURL:_networkDirectoryURL];
-
-  return YES;
-}
-
-- (void)excludeFromBackupForURL:(NSURL *)url {
-  if (!url.path) {
-    return;
-  }
-
-  // Set the iCloud exclusion attribute on the Documents URL.
-  NSError *preventBackupError = nil;
-  [url setResourceValue:@YES forKey:NSURLIsExcludedFromBackupKey error:&preventBackupError];
-  if (preventBackupError) {
-    [_loggerDelegate firNetwork_logWithLevel:kFIRNetworkLogLevelError
-                                 messageCode:kFIRNetworkMessageCodeURLSession016
-                                     message:@"Cannot exclude temporary folder from iTunes backup"];
-  }
-}
-
-- (void)URLSession:(NSURLSession *)session
-                          task:(NSURLSessionTask *)task
-    willPerformHTTPRedirection:(NSHTTPURLResponse *)response
-                    newRequest:(NSURLRequest *)request
-             completionHandler:(void (^)(NSURLRequest *))completionHandler {
-  NSArray *nonAllowedRedirectionCodes = @[
-    @(kFIRNetworkHTTPStatusCodeFound), @(kFIRNetworkHTTPStatusCodeMovedPermanently),
-    @(kFIRNetworkHTTPStatusCodeMovedTemporarily), @(kFIRNetworkHTTPStatusCodeMultipleChoices)
-  ];
-
-  // Allow those not in the non allowed list to be followed.
-  if (![nonAllowedRedirectionCodes containsObject:@(response.statusCode)]) {
-    completionHandler(request);
-    return;
-  }
-
-  // Do not allow redirection if the response code is in the non-allowed list.
-  NSURLRequest *newRequest = request;
-
-  if (response) {
-    newRequest = nil;
-  }
-
-  completionHandler(newRequest);
-}
-
-#pragma mark - Helper Methods
-
-- (void)callCompletionHandler:(FIRNetworkURLSessionCompletionHandler)handler
-                 withResponse:(NSHTTPURLResponse *)response
-                         data:(NSData *)data
-                        error:(NSError *)error {
-  if (error) {
-    [_loggerDelegate firNetwork_logWithLevel:kFIRNetworkLogLevelError
-                                 messageCode:kFIRNetworkMessageCodeURLSession017
-                                     message:@"Encounter network error. Code, error"
-                                    contexts:@[ @(error.code), error ]];
-  }
-
-  if (handler) {
-    dispatch_async(dispatch_get_main_queue(), ^{
-      handler(response, data, self->_sessionID, error);
-    });
-  }
-}
-
-- (void)populateSessionConfig:(NSURLSessionConfiguration *)sessionConfig
-                  withRequest:(NSURLRequest *)request {
-  sessionConfig.HTTPAdditionalHeaders = request.allHTTPHeaderFields;
-  sessionConfig.timeoutIntervalForRequest = request.timeoutInterval;
-  sessionConfig.timeoutIntervalForResource = request.timeoutInterval;
-  sessionConfig.requestCachePolicy = request.cachePolicy;
-}
-
-@end
diff --git a/Firebase/Core/FIRReachabilityChecker.m b/Firebase/Core/FIRReachabilityChecker.m
deleted file mode 100644
index cac87ff..0000000
--- a/Firebase/Core/FIRReachabilityChecker.m
+++ /dev/null
@@ -1,256 +0,0 @@
-// Copyright 2017 Google
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#import <Foundation/Foundation.h>
-
-#import "Private/FIRReachabilityChecker+Internal.h"
-#import "Private/FIRReachabilityChecker.h"
-
-#import "Private/FIRLogger.h"
-#import "Private/FIRNetwork.h"
-#import "Private/FIRNetworkMessageCode.h"
-
-static void ReachabilityCallback(SCNetworkReachabilityRef reachability,
-                                 SCNetworkReachabilityFlags flags,
-                                 void *info);
-
-static const struct FIRReachabilityApi kFIRDefaultReachabilityApi = {
-    SCNetworkReachabilityCreateWithName,
-    SCNetworkReachabilitySetCallback,
-    SCNetworkReachabilityScheduleWithRunLoop,
-    SCNetworkReachabilityUnscheduleFromRunLoop,
-    CFRelease,
-};
-
-static NSString *const kFIRReachabilityUnknownStatus = @"Unknown";
-static NSString *const kFIRReachabilityConnectedStatus = @"Connected";
-static NSString *const kFIRReachabilityDisconnectedStatus = @"Disconnected";
-
-@interface FIRReachabilityChecker ()
-
-@property(nonatomic, assign) const struct FIRReachabilityApi *reachabilityApi;
-@property(nonatomic, assign) FIRReachabilityStatus reachabilityStatus;
-@property(nonatomic, copy) NSString *host;
-@property(nonatomic, assign) SCNetworkReachabilityRef reachability;
-
-@end
-
-@implementation FIRReachabilityChecker
-
-@synthesize reachabilityApi = reachabilityApi_;
-@synthesize reachability = reachability_;
-
-- (const struct FIRReachabilityApi *)reachabilityApi {
-  return reachabilityApi_;
-}
-
-- (void)setReachabilityApi:(const struct FIRReachabilityApi *)reachabilityApi {
-  if (reachability_) {
-    NSString *message =
-        @"Cannot change reachability API while reachability is running. "
-        @"Call stop first.";
-    [loggerDelegate_ firNetwork_logWithLevel:kFIRNetworkLogLevelError
-                                 messageCode:kFIRNetworkMessageCodeReachabilityChecker000
-                                     message:message];
-    return;
-  }
-  reachabilityApi_ = reachabilityApi;
-}
-
-@synthesize reachabilityStatus = reachabilityStatus_;
-@synthesize host = host_;
-@synthesize reachabilityDelegate = reachabilityDelegate_;
-@synthesize loggerDelegate = loggerDelegate_;
-
-- (BOOL)isActive {
-  return reachability_ != nil;
-}
-
-- (void)setReachabilityDelegate:(id<FIRReachabilityDelegate>)reachabilityDelegate {
-  if (reachabilityDelegate &&
-      (![(NSObject *)reachabilityDelegate conformsToProtocol:@protocol(FIRReachabilityDelegate)])) {
-    FIRLogError(kFIRLoggerCore,
-                [NSString stringWithFormat:@"I-NET%06ld",
-                                           (long)kFIRNetworkMessageCodeReachabilityChecker005],
-                @"Reachability delegate doesn't conform to Reachability protocol.");
-    return;
-  }
-  reachabilityDelegate_ = reachabilityDelegate;
-}
-
-- (void)setLoggerDelegate:(id<FIRNetworkLoggerDelegate>)loggerDelegate {
-  if (loggerDelegate &&
-      (![(NSObject *)loggerDelegate conformsToProtocol:@protocol(FIRNetworkLoggerDelegate)])) {
-    FIRLogError(kFIRLoggerCore,
-                [NSString stringWithFormat:@"I-NET%06ld",
-                                           (long)kFIRNetworkMessageCodeReachabilityChecker006],
-                @"Reachability delegate doesn't conform to Logger protocol.");
-    return;
-  }
-  loggerDelegate_ = loggerDelegate;
-}
-
-- (instancetype)initWithReachabilityDelegate:(id<FIRReachabilityDelegate>)reachabilityDelegate
-                              loggerDelegate:(id<FIRNetworkLoggerDelegate>)loggerDelegate
-                                    withHost:(NSString *)host {
-  self = [super init];
-
-  [self setLoggerDelegate:loggerDelegate];
-
-  if (!host || !host.length) {
-    [loggerDelegate_ firNetwork_logWithLevel:kFIRNetworkLogLevelError
-                                 messageCode:kFIRNetworkMessageCodeReachabilityChecker001
-                                     message:@"Invalid host specified"];
-    return nil;
-  }
-  if (self) {
-    [self setReachabilityDelegate:reachabilityDelegate];
-    reachabilityApi_ = &kFIRDefaultReachabilityApi;
-    reachabilityStatus_ = kFIRReachabilityUnknown;
-    host_ = [host copy];
-    reachability_ = nil;
-  }
-  return self;
-}
-
-- (void)dealloc {
-  reachabilityDelegate_ = nil;
-  loggerDelegate_ = nil;
-  [self stop];
-}
-
-- (BOOL)start {
-  if (!reachability_) {
-    reachability_ = reachabilityApi_->createWithNameFn(kCFAllocatorDefault, [host_ UTF8String]);
-    if (!reachability_) {
-      return NO;
-    }
-    SCNetworkReachabilityContext context = {
-        0,                       /* version */
-        (__bridge void *)(self), /* info (passed as last parameter to reachability callback) */
-        NULL,                    /* retain */
-        NULL,                    /* release */
-        NULL                     /* copyDescription */
-    };
-    if (!reachabilityApi_->setCallbackFn(reachability_, ReachabilityCallback, &context) ||
-        !reachabilityApi_->scheduleWithRunLoopFn(reachability_, CFRunLoopGetMain(),
-                                                 kCFRunLoopCommonModes)) {
-      reachabilityApi_->releaseFn(reachability_);
-      reachability_ = nil;
-      [loggerDelegate_ firNetwork_logWithLevel:kFIRNetworkLogLevelError
-                                   messageCode:kFIRNetworkMessageCodeReachabilityChecker002
-                                       message:@"Failed to start reachability handle"];
-      return NO;
-    }
-  }
-  [loggerDelegate_ firNetwork_logWithLevel:kFIRNetworkLogLevelDebug
-                               messageCode:kFIRNetworkMessageCodeReachabilityChecker003
-                                   message:@"Monitoring the network status"];
-  return YES;
-}
-
-- (void)stop {
-  if (reachability_) {
-    reachabilityStatus_ = kFIRReachabilityUnknown;
-    reachabilityApi_->unscheduleFromRunLoopFn(reachability_, CFRunLoopGetMain(),
-                                              kCFRunLoopCommonModes);
-    reachabilityApi_->releaseFn(reachability_);
-    reachability_ = nil;
-  }
-}
-
-- (FIRReachabilityStatus)statusForFlags:(SCNetworkReachabilityFlags)flags {
-  FIRReachabilityStatus status = kFIRReachabilityNotReachable;
-  // If the Reachable flag is not set, we definitely don't have connectivity.
-  if (flags & kSCNetworkReachabilityFlagsReachable) {
-    // Reachable flag is set. Check further flags.
-    if (!(flags & kSCNetworkReachabilityFlagsConnectionRequired)) {
-// Connection required flag is not set, so we have connectivity.
-#if TARGET_OS_IOS || TARGET_OS_TV
-      status = (flags & kSCNetworkReachabilityFlagsIsWWAN) ? kFIRReachabilityViaCellular
-                                                           : kFIRReachabilityViaWifi;
-#elif TARGET_OS_OSX
-      status = kFIRReachabilityViaWifi;
-#endif
-    } else if ((flags & (kSCNetworkReachabilityFlagsConnectionOnDemand |
-                         kSCNetworkReachabilityFlagsConnectionOnTraffic)) &&
-               !(flags & kSCNetworkReachabilityFlagsInterventionRequired)) {
-// If the connection on demand or connection on traffic flag is set, and user intervention
-// is not required, we have connectivity.
-#if TARGET_OS_IOS || TARGET_OS_TV
-      status = (flags & kSCNetworkReachabilityFlagsIsWWAN) ? kFIRReachabilityViaCellular
-                                                           : kFIRReachabilityViaWifi;
-#elif TARGET_OS_OSX
-      status = kFIRReachabilityViaWifi;
-#endif
-    }
-  }
-  return status;
-}
-
-- (void)reachabilityFlagsChanged:(SCNetworkReachabilityFlags)flags {
-  FIRReachabilityStatus status = [self statusForFlags:flags];
-  if (reachabilityStatus_ != status) {
-    NSString *reachabilityStatusString;
-    if (status == kFIRReachabilityUnknown) {
-      reachabilityStatusString = kFIRReachabilityUnknownStatus;
-    } else {
-      reachabilityStatusString = (status == kFIRReachabilityNotReachable)
-                                     ? kFIRReachabilityDisconnectedStatus
-                                     : kFIRReachabilityConnectedStatus;
-    }
-    [loggerDelegate_ firNetwork_logWithLevel:kFIRNetworkLogLevelDebug
-                                 messageCode:kFIRNetworkMessageCodeReachabilityChecker004
-                                     message:@"Network status has changed. Code, status"
-                                    contexts:@[ @(status), reachabilityStatusString ]];
-    reachabilityStatus_ = status;
-    [reachabilityDelegate_ reachability:self statusChanged:reachabilityStatus_];
-  }
-}
-
-@end
-
-static void ReachabilityCallback(SCNetworkReachabilityRef reachability,
-                                 SCNetworkReachabilityFlags flags,
-                                 void *info) {
-  FIRReachabilityChecker *checker = (__bridge FIRReachabilityChecker *)info;
-  [checker reachabilityFlagsChanged:flags];
-}
-
-// This function used to be at the top of the file, but it was moved here
-// as a workaround for a suspected compiler bug. When compiled in Release mode
-// and run on an iOS device with WiFi disabled, the reachability code crashed
-// when calling SCNetworkReachabilityScheduleWithRunLoop, or shortly thereafter.
-// After unsuccessfully trying to diagnose the cause of the crash, it was
-// discovered that moving this function to the end of the file magically fixed
-// the crash. If you are going to edit this file, exercise caution and make sure
-// to test thoroughly with an iOS device under various network conditions.
-const NSString *FIRReachabilityStatusString(FIRReachabilityStatus status) {
-  switch (status) {
-    case kFIRReachabilityUnknown:
-      return @"Reachability Unknown";
-
-    case kFIRReachabilityNotReachable:
-      return @"Not reachable";
-
-    case kFIRReachabilityViaWifi:
-      return @"Reachable via Wifi";
-
-    case kFIRReachabilityViaCellular:
-      return @"Reachable via Cellular Data";
-
-    default:
-      return [NSString stringWithFormat:@"Invalid reachability status %d", (int)status];
-  }
-}
diff --git a/Firebase/Core/FIRVersion.m b/Firebase/Core/FIRVersion.m
index 97cd1bc..ec0f6ba 100644
--- a/Firebase/Core/FIRVersion.m
+++ b/Firebase/Core/FIRVersion.m
@@ -29,5 +29,5 @@
 #define STR(x) STR_EXPAND(x)
 #define STR_EXPAND(x) #x
 
-const unsigned char *const FIRVersionString = (const unsigned char *const)STR(Firebase_VERSION);
-const unsigned char *const FIRCoreVersionString = (const unsigned char *const)STR(FIRCore_VERSION);
+const char *const FIRVersionString = (const char *const)STR(Firebase_VERSION);
+const char *const FIRCoreVersionString = (const char *const)STR(FIRCore_VERSION);
diff --git a/Firebase/Core/Private/FIRMutableDictionary.h b/Firebase/Core/Private/FIRMutableDictionary.h
deleted file mode 100644
index 6829dbc..0000000
--- a/Firebase/Core/Private/FIRMutableDictionary.h
+++ /dev/null
@@ -1,46 +0,0 @@
-/*
- * Copyright 2017 Google
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#import <Foundation/Foundation.h>
-
-/// A mutable dictionary that provides atomic accessor and mutators.
-@interface FIRMutableDictionary : NSObject
-
-/// Returns an object given a key in the dictionary or nil if not found.
-- (id)objectForKey:(id)key;
-
-/// Updates the object given its key or adds it to the dictionary if it is not in the dictionary.
-- (void)setObject:(id)object forKey:(id<NSCopying>)key;
-
-/// Removes the object given its session ID from the dictionary.
-- (void)removeObjectForKey:(id)key;
-
-/// Removes all objects.
-- (void)removeAllObjects;
-
-/// Returns the number of current objects in the dictionary.
-- (NSUInteger)count;
-
-/// Returns an object given a key in the dictionary or nil if not found.
-- (id)objectForKeyedSubscript:(id<NSCopying>)key;
-
-/// Updates the object given its key or adds it to the dictionary if it is not in the dictionary.
-- (void)setObject:(id)obj forKeyedSubscript:(id<NSCopying>)key;
-
-/// Returns the immutable dictionary.
-- (NSDictionary *)dictionary;
-
-@end
diff --git a/Firebase/Core/Private/FIRNetwork.h b/Firebase/Core/Private/FIRNetwork.h
deleted file mode 100644
index 32be35a..0000000
--- a/Firebase/Core/Private/FIRNetwork.h
+++ /dev/null
@@ -1,87 +0,0 @@
-/*
- * Copyright 2017 Google
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#import <Foundation/Foundation.h>
-
-#import "FIRNetworkConstants.h"
-#import "FIRNetworkLoggerProtocol.h"
-#import "FIRNetworkURLSession.h"
-
-/// Delegate protocol for FIRNetwork events.
-@protocol FIRNetworkReachabilityDelegate
-
-/// Tells the delegate to handle events when the network reachability changes to connected or not
-/// connected.
-- (void)reachabilityDidChange;
-
-@end
-
-/// The Network component that provides network status and handles network requests and responses.
-/// This is not thread safe.
-///
-/// NOTE:
-/// User must add FIRAnalytics handleEventsForBackgroundURLSessionID:completionHandler to the
-/// AppDelegate application:handleEventsForBackgroundURLSession:completionHandler:
-@interface FIRNetwork : NSObject
-
-/// Indicates if network connectivity is available.
-@property(nonatomic, readonly, getter=isNetworkConnected) BOOL networkConnected;
-
-/// Indicates if there are any uploads in progress.
-@property(nonatomic, readonly, getter=hasUploadInProgress) BOOL uploadInProgress;
-
-/// An optional delegate that can be used in the event when network reachability changes.
-@property(nonatomic, weak) id<FIRNetworkReachabilityDelegate> reachabilityDelegate;
-
-/// An optional delegate that can be used to log messages, warnings or errors that occur in the
-/// network operations.
-@property(nonatomic, weak) id<FIRNetworkLoggerDelegate> loggerDelegate;
-
-/// Indicates whether the logger should display debug messages.
-@property(nonatomic, assign) BOOL isDebugModeEnabled;
-
-/// The time interval in seconds for the network request to timeout.
-@property(nonatomic, assign) NSTimeInterval timeoutInterval;
-
-/// Initializes with the default reachability host.
-- (instancetype)init;
-
-/// Initializes with a custom reachability host.
-- (instancetype)initWithReachabilityHost:(NSString *)reachabilityHost;
-
-/// Handles events when background session with the given ID has finished.
-+ (void)handleEventsForBackgroundURLSessionID:(NSString *)sessionID
-                            completionHandler:(FIRNetworkSystemCompletionHandler)completionHandler;
-
-/// Compresses and sends a POST request with the provided data to the URL. The session will be
-/// background session if usingBackgroundSession is YES. Otherwise, the POST session is default
-/// session. Returns a session ID or nil if an error occurs.
-- (NSString *)postURL:(NSURL *)url
-                   payload:(NSData *)payload
-                     queue:(dispatch_queue_t)queue
-    usingBackgroundSession:(BOOL)usingBackgroundSession
-         completionHandler:(FIRNetworkCompletionHandler)handler;
-
-/// Sends a GET request with the provided data to the URL. The session will be background session
-/// if usingBackgroundSession is YES. Otherwise, the GET session is default session. Returns a
-/// session ID or nil if an error occurs.
-- (NSString *)getURL:(NSURL *)url
-                   headers:(NSDictionary *)headers
-                     queue:(dispatch_queue_t)queue
-    usingBackgroundSession:(BOOL)usingBackgroundSession
-         completionHandler:(FIRNetworkCompletionHandler)handler;
-
-@end
diff --git a/Firebase/Core/Private/FIRNetworkConstants.h b/Firebase/Core/Private/FIRNetworkConstants.h
deleted file mode 100644
index d318581..0000000
--- a/Firebase/Core/Private/FIRNetworkConstants.h
+++ /dev/null
@@ -1,75 +0,0 @@
-/*
- * Copyright 2017 Google
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#import <Foundation/Foundation.h>
-
-/// Error codes in Firebase Network error domain.
-/// Note: these error codes should never change. It would make it harder to decode the errors if
-/// we inadvertently altered any of these codes in a future SDK version.
-typedef NS_ENUM(NSInteger, FIRNetworkErrorCode) {
-  /// Unknown error.
-  FIRNetworkErrorCodeUnknown = 0,
-  /// Error occurs when the request URL is invalid.
-  FIRErrorCodeNetworkInvalidURL = 1,
-  /// Error occurs when request cannot be constructed.
-  FIRErrorCodeNetworkRequestCreation = 2,
-  /// Error occurs when payload cannot be compressed.
-  FIRErrorCodeNetworkPayloadCompression = 3,
-  /// Error occurs when session task cannot be created.
-  FIRErrorCodeNetworkSessionTaskCreation = 4,
-  /// Error occurs when there is no response.
-  FIRErrorCodeNetworkInvalidResponse = 5
-};
-
-#pragma mark - Network constants
-
-/// The prefix of the ID of the background session.
-extern NSString *const kFIRNetworkBackgroundSessionConfigIDPrefix;
-
-/// The sub directory to store the files of data that is being uploaded in the background.
-extern NSString *const kFIRNetworkApplicationSupportSubdirectory;
-
-/// Name of the temporary directory that stores files for background uploading.
-extern NSString *const kFIRNetworkTempDirectoryName;
-
-/// The period when the temporary uploading file can stay.
-extern const NSTimeInterval kFIRNetworkTempFolderExpireTime;
-
-/// The default network request timeout interval.
-extern const NSTimeInterval kFIRNetworkTimeOutInterval;
-
-/// The host to check the reachability of the network.
-extern NSString *const kFIRNetworkReachabilityHost;
-
-/// The key to get the error context of the UserInfo.
-extern NSString *const kFIRNetworkErrorContext;
-
-#pragma mark - Network Status Code
-
-extern const int kFIRNetworkHTTPStatusOK;
-extern const int kFIRNetworkHTTPStatusNoContent;
-extern const int kFIRNetworkHTTPStatusCodeMultipleChoices;
-extern const int kFIRNetworkHTTPStatusCodeMovedPermanently;
-extern const int kFIRNetworkHTTPStatusCodeFound;
-extern const int kFIRNetworkHTTPStatusCodeNotModified;
-extern const int kFIRNetworkHTTPStatusCodeMovedTemporarily;
-extern const int kFIRNetworkHTTPStatusCodeNotFound;
-extern const int kFIRNetworkHTTPStatusCodeCannotAcceptTraffic;
-extern const int kFIRNetworkHTTPStatusCodeUnavailable;
-
-#pragma mark - Error Domain
-
-extern NSString *const kFIRNetworkErrorDomain;
diff --git a/Firebase/Core/Private/FIRNetworkLoggerProtocol.h b/Firebase/Core/Private/FIRNetworkLoggerProtocol.h
deleted file mode 100644
index add70fc..0000000
--- a/Firebase/Core/Private/FIRNetworkLoggerProtocol.h
+++ /dev/null
@@ -1,50 +0,0 @@
-/*
- * Copyright 2017 Google
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#import <Foundation/Foundation.h>
-
-#import "FIRLoggerLevel.h"
-#import "FIRNetworkMessageCode.h"
-
-/// The log levels used by FIRNetworkLogger.
-typedef NS_ENUM(NSInteger, FIRNetworkLogLevel) {
-  kFIRNetworkLogLevelError = FIRLoggerLevelError,
-  kFIRNetworkLogLevelWarning = FIRLoggerLevelWarning,
-  kFIRNetworkLogLevelInfo = FIRLoggerLevelInfo,
-  kFIRNetworkLogLevelDebug = FIRLoggerLevelDebug,
-};
-
-@protocol FIRNetworkLoggerDelegate <NSObject>
-
-@required
-/// Tells the delegate to log a message with an array of contexts and the log level.
-- (void)firNetwork_logWithLevel:(FIRNetworkLogLevel)logLevel
-                    messageCode:(FIRNetworkMessageCode)messageCode
-                        message:(NSString *)message
-                       contexts:(NSArray *)contexts;
-
-/// Tells the delegate to log a message with a context and the log level.
-- (void)firNetwork_logWithLevel:(FIRNetworkLogLevel)logLevel
-                    messageCode:(FIRNetworkMessageCode)messageCode
-                        message:(NSString *)message
-                        context:(id)context;
-
-/// Tells the delegate to log a message with the log level.
-- (void)firNetwork_logWithLevel:(FIRNetworkLogLevel)logLevel
-                    messageCode:(FIRNetworkMessageCode)messageCode
-                        message:(NSString *)message;
-
-@end
diff --git a/Firebase/Core/Private/FIRNetworkMessageCode.h b/Firebase/Core/Private/FIRNetworkMessageCode.h
deleted file mode 100644
index 30f562f..0000000
--- a/Firebase/Core/Private/FIRNetworkMessageCode.h
+++ /dev/null
@@ -1,52 +0,0 @@
-/*
- * Copyright 2017 Google
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-// Make sure these codes do not overlap with any contained in the FIRAMessageCode enum.
-typedef NS_ENUM(NSInteger, FIRNetworkMessageCode) {
-  // FIRNetwork.m
-  kFIRNetworkMessageCodeNetwork000 = 900000,  // I-NET900000
-  kFIRNetworkMessageCodeNetwork001 = 900001,  // I-NET900001
-  kFIRNetworkMessageCodeNetwork002 = 900002,  // I-NET900002
-  kFIRNetworkMessageCodeNetwork003 = 900003,  // I-NET900003
-  // FIRNetworkURLSession.m
-  kFIRNetworkMessageCodeURLSession000 = 901000,  // I-NET901000
-  kFIRNetworkMessageCodeURLSession001 = 901001,  // I-NET901001
-  kFIRNetworkMessageCodeURLSession002 = 901002,  // I-NET901002
-  kFIRNetworkMessageCodeURLSession003 = 901003,  // I-NET901003
-  kFIRNetworkMessageCodeURLSession004 = 901004,  // I-NET901004
-  kFIRNetworkMessageCodeURLSession005 = 901005,  // I-NET901005
-  kFIRNetworkMessageCodeURLSession006 = 901006,  // I-NET901006
-  kFIRNetworkMessageCodeURLSession007 = 901007,  // I-NET901007
-  kFIRNetworkMessageCodeURLSession008 = 901008,  // I-NET901008
-  kFIRNetworkMessageCodeURLSession009 = 901009,  // I-NET901009
-  kFIRNetworkMessageCodeURLSession010 = 901010,  // I-NET901010
-  kFIRNetworkMessageCodeURLSession011 = 901011,  // I-NET901011
-  kFIRNetworkMessageCodeURLSession012 = 901012,  // I-NET901012
-  kFIRNetworkMessageCodeURLSession013 = 901013,  // I-NET901013
-  kFIRNetworkMessageCodeURLSession014 = 901014,  // I-NET901014
-  kFIRNetworkMessageCodeURLSession015 = 901015,  // I-NET901015
-  kFIRNetworkMessageCodeURLSession016 = 901016,  // I-NET901016
-  kFIRNetworkMessageCodeURLSession017 = 901017,  // I-NET901017
-  kFIRNetworkMessageCodeURLSession018 = 901018,  // I-NET901018
-  // FIRReachabilityChecker.m
-  kFIRNetworkMessageCodeReachabilityChecker000 = 902000,  // I-NET902000
-  kFIRNetworkMessageCodeReachabilityChecker001 = 902001,  // I-NET902001
-  kFIRNetworkMessageCodeReachabilityChecker002 = 902002,  // I-NET902002
-  kFIRNetworkMessageCodeReachabilityChecker003 = 902003,  // I-NET902003
-  kFIRNetworkMessageCodeReachabilityChecker004 = 902004,  // I-NET902004
-  kFIRNetworkMessageCodeReachabilityChecker005 = 902005,  // I-NET902005
-  kFIRNetworkMessageCodeReachabilityChecker006 = 902006,  // I-NET902006
-};
diff --git a/Firebase/Core/Private/FIRNetworkURLSession.h b/Firebase/Core/Private/FIRNetworkURLSession.h
deleted file mode 100644
index a51b8a9..0000000
--- a/Firebase/Core/Private/FIRNetworkURLSession.h
+++ /dev/null
@@ -1,60 +0,0 @@
-/*
- * Copyright 2017 Google
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#import <Foundation/Foundation.h>
-
-#import "FIRNetworkLoggerProtocol.h"
-
-typedef void (^FIRNetworkCompletionHandler)(NSHTTPURLResponse *response,
-                                            NSData *data,
-                                            NSError *error);
-typedef void (^FIRNetworkURLSessionCompletionHandler)(NSHTTPURLResponse *response,
-                                                      NSData *data,
-                                                      NSString *sessionID,
-                                                      NSError *error);
-typedef void (^FIRNetworkSystemCompletionHandler)(void);
-
-/// The protocol that uses NSURLSession for iOS >= 7.0 to handle requests and responses.
-@interface FIRNetworkURLSession
-    : NSObject <NSURLSessionDelegate, NSURLSessionTaskDelegate, NSURLSessionDownloadDelegate>
-
-/// Indicates whether the background network is enabled. Default value is NO.
-@property(nonatomic, getter=isBackgroundNetworkEnabled) BOOL backgroundNetworkEnabled;
-
-/// The logger delegate to log message, errors or warnings that occur during the network operations.
-@property(nonatomic, weak) id<FIRNetworkLoggerDelegate> loggerDelegate;
-
-/// Calls the system provided completion handler after the background session is finished.
-+ (void)handleEventsForBackgroundURLSessionID:(NSString *)sessionID
-                            completionHandler:(FIRNetworkSystemCompletionHandler)completionHandler;
-
-/// Initializes with logger delegate.
-- (instancetype)initWithNetworkLoggerDelegate:(id<FIRNetworkLoggerDelegate>)networkLoggerDelegate
-    NS_DESIGNATED_INITIALIZER;
-
-- (instancetype)init NS_UNAVAILABLE;
-
-/// Sends an asynchronous POST request and calls the provided completion handler when the request
-/// completes or when errors occur, and returns an ID of the session/connection.
-- (NSString *)sessionIDFromAsyncPOSTRequest:(NSURLRequest *)request
-                          completionHandler:(FIRNetworkURLSessionCompletionHandler)handler;
-
-/// Sends an asynchronous GET request and calls the provided completion handler when the request
-/// completes or when errors occur, and returns an ID of the session.
-- (NSString *)sessionIDFromAsyncGETRequest:(NSURLRequest *)request
-                         completionHandler:(FIRNetworkURLSessionCompletionHandler)handler;
-
-@end
diff --git a/Firebase/Core/Private/FIRReachabilityChecker+Internal.h b/Firebase/Core/Private/FIRReachabilityChecker+Internal.h
deleted file mode 100644
index f82d103..0000000
--- a/Firebase/Core/Private/FIRReachabilityChecker+Internal.h
+++ /dev/null
@@ -1,47 +0,0 @@
-/*
- * Copyright 2017 Google
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#import "FIRReachabilityChecker.h"
-
-typedef SCNetworkReachabilityRef (*FIRReachabilityCreateWithNameFn)(CFAllocatorRef allocator,
-                                                                    const char *host);
-
-typedef Boolean (*FIRReachabilitySetCallbackFn)(SCNetworkReachabilityRef target,
-                                                SCNetworkReachabilityCallBack callback,
-                                                SCNetworkReachabilityContext *context);
-typedef Boolean (*FIRReachabilityScheduleWithRunLoopFn)(SCNetworkReachabilityRef target,
-                                                        CFRunLoopRef runLoop,
-                                                        CFStringRef runLoopMode);
-typedef Boolean (*FIRReachabilityUnscheduleFromRunLoopFn)(SCNetworkReachabilityRef target,
-                                                          CFRunLoopRef runLoop,
-                                                          CFStringRef runLoopMode);
-
-typedef void (*FIRReachabilityReleaseFn)(CFTypeRef cf);
-
-struct FIRReachabilityApi {
-  FIRReachabilityCreateWithNameFn createWithNameFn;
-  FIRReachabilitySetCallbackFn setCallbackFn;
-  FIRReachabilityScheduleWithRunLoopFn scheduleWithRunLoopFn;
-  FIRReachabilityUnscheduleFromRunLoopFn unscheduleFromRunLoopFn;
-  FIRReachabilityReleaseFn releaseFn;
-};
-
-@interface FIRReachabilityChecker (Internal)
-
-- (const struct FIRReachabilityApi *)reachabilityApi;
-- (void)setReachabilityApi:(const struct FIRReachabilityApi *)reachabilityApi;
-
-@end
diff --git a/Firebase/Core/Private/FIRReachabilityChecker.h b/Firebase/Core/Private/FIRReachabilityChecker.h
deleted file mode 100644
index 3a6a531..0000000
--- a/Firebase/Core/Private/FIRReachabilityChecker.h
+++ /dev/null
@@ -1,83 +0,0 @@
-/*
- * Copyright 2017 Google
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#import <Foundation/Foundation.h>
-#import <SystemConfiguration/SystemConfiguration.h>
-
-/// Reachability Status
-typedef enum {
-  kFIRReachabilityUnknown,  ///< Have not yet checked or been notified whether host is reachable.
-  kFIRReachabilityNotReachable,  ///< Host is not reachable.
-  kFIRReachabilityViaWifi,       ///< Host is reachable via Wifi.
-  kFIRReachabilityViaCellular,   ///< Host is reachable via cellular.
-} FIRReachabilityStatus;
-
-const NSString *FIRReachabilityStatusString(FIRReachabilityStatus status);
-
-@class FIRReachabilityChecker;
-@protocol FIRNetworkLoggerDelegate;
-
-/// Google Analytics iOS Reachability Checker.
-@protocol FIRReachabilityDelegate
-@required
-/// Called when network status has changed.
-- (void)reachability:(FIRReachabilityChecker *)reachability
-       statusChanged:(FIRReachabilityStatus)status;
-@end
-
-/// Google Analytics iOS Network Status Checker.
-@interface FIRReachabilityChecker : NSObject
-
-/// The last known reachability status, or FIRReachabilityStatusUnknown if the
-/// checker is not active.
-@property(nonatomic, readonly) FIRReachabilityStatus reachabilityStatus;
-/// The host to which reachability status is to be checked.
-@property(nonatomic, copy, readonly) NSString *host;
-/// The delegate to be notified of reachability status changes.
-@property(nonatomic, weak) id<FIRReachabilityDelegate> reachabilityDelegate;
-/// The delegate to be notified to log messages.
-@property(nonatomic, weak) id<FIRNetworkLoggerDelegate> loggerDelegate;
-/// `YES` if the reachability checker is active, `NO` otherwise.
-@property(nonatomic, readonly) BOOL isActive;
-
-/// Initialize the reachability checker. Note that you must call start to begin checking for and
-/// receiving notifications about network status changes.
-///
-/// @param reachabilityDelegate The delegate to be notified when reachability status to host
-/// changes.
-///
-/// @param loggerDelegate The delegate to send log messages to.
-///
-/// @param host The name of the host.
-///
-- (instancetype)initWithReachabilityDelegate:(id<FIRReachabilityDelegate>)reachabilityDelegate
-                              loggerDelegate:(id<FIRNetworkLoggerDelegate>)loggerDelegate
-                                    withHost:(NSString *)host;
-
-- (instancetype)init NS_UNAVAILABLE;
-
-/// Start checking for reachability to the specified host. This has no effect if the status
-/// checker is already checking for connectivity.
-///
-/// @return `YES` if initiating status checking was successful or the status checking has already
-/// been initiated, `NO` otherwise.
-- (BOOL)start;
-
-/// Stop checking for reachability to the specified host. This has no effect if the status
-/// checker is not checking for connectivity.
-- (void)stop;
-
-@end
diff --git a/Firebase/Core/Private/FIRVersion.h b/Firebase/Core/Private/FIRVersion.h
index cec0994..226efb1 100644
--- a/Firebase/Core/Private/FIRVersion.h
+++ b/Firebase/Core/Private/FIRVersion.h
@@ -17,7 +17,7 @@
 #import <Foundation/Foundation.h>
 
 /** The version of the Firebase SDK. */
-FOUNDATION_EXPORT const unsigned char *const FIRVersionString;
+FOUNDATION_EXPORT const char *const FIRVersionString;
 
 /** The version of the FirebaseCore Component. */
-FOUNDATION_EXPORT const unsigned char *const FIRCoreVersionString;
+FOUNDATION_EXPORT const char *const FIRCoreVersionString;
diff --git a/Firebase/Core/Public/FIRLoggerLevel.h b/Firebase/Core/Public/FIRLoggerLevel.h
index 8b6579f..e17e338 100644
--- a/Firebase/Core/Public/FIRLoggerLevel.h
+++ b/Firebase/Core/Public/FIRLoggerLevel.h
@@ -14,6 +14,9 @@
  * limitations under the License.
  */
 
+// Note that importing GULLoggerLevel.h will lead to a non-modular header
+// import error.
+
 /**
  * The log levels used by internal logging.
  */
diff --git a/Firebase/Core/third_party/FIRAppEnvironmentUtil.h b/Firebase/Core/third_party/FIRAppEnvironmentUtil.h
deleted file mode 100644
index 09ee504..0000000
--- a/Firebase/Core/third_party/FIRAppEnvironmentUtil.h
+++ /dev/null
@@ -1,43 +0,0 @@
-/*
- * Copyright 2017 Google
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#import <Foundation/Foundation.h>
-
-@interface FIRAppEnvironmentUtil : NSObject
-
-/// Indicates whether the app is from Apple Store or not. Returns NO if the app is on simulator,
-/// development environment or sideloaded.
-+ (BOOL)isFromAppStore;
-
-/// Indicates whether the app is a Testflight app. Returns YES if the app has sandbox receipt.
-/// Returns NO otherwise.
-+ (BOOL)isAppStoreReceiptSandbox;
-
-/// Indicates whether the app is on simulator or not at runtime depending on the device
-/// architecture.
-+ (BOOL)isSimulator;
-
-/// The current device model. Returns an empty string if device model cannot be retrieved.
-+ (NSString *)deviceModel;
-
-/// The current operating system version. Returns an empty string if the system version cannot be
-/// retrieved.
-+ (NSString *)systemVersion;
-
-/// Indicates whether it is running inside an extension or an app.
-+ (BOOL)isAppExtension;
-
-@end
diff --git a/Firebase/Core/third_party/FIRAppEnvironmentUtil.m b/Firebase/Core/third_party/FIRAppEnvironmentUtil.m
deleted file mode 100644
index be4e971..0000000
--- a/Firebase/Core/third_party/FIRAppEnvironmentUtil.m
+++ /dev/null
@@ -1,239 +0,0 @@
-// Copyright 2017 Google
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#import <Foundation/Foundation.h>
-
-#import "FIRAppEnvironmentUtil.h"
-
-#import <dlfcn.h>
-#import <mach-o/dyld.h>
-#import <sys/utsname.h>
-
-/// The encryption info struct and constants are missing from the iPhoneSimulator SDK, but not from
-/// the iPhoneOS or Mac OS X SDKs. Since one doesn't ever ship a Simulator binary, we'll just
-/// provide the definitions here.
-#if TARGET_OS_SIMULATOR && !defined(LC_ENCRYPTION_INFO)
-#define LC_ENCRYPTION_INFO 0x21
-struct encryption_info_command {
-  uint32_t cmd;
-  uint32_t cmdsize;
-  uint32_t cryptoff;
-  uint32_t cryptsize;
-  uint32_t cryptid;
-};
-#endif
-
-@implementation FIRAppEnvironmentUtil
-
-/// A key for the Info.plist to enable or disable checking if the App Store is running in a sandbox.
-/// This will affect your data integrity when using Firebase Analytics, as it will disable some
-/// necessary checks.
-static NSString *const kFIRAppStoreReceiptURLCheckEnabledKey =
-    @"FirebaseAppStoreReceiptURLCheckEnabled";
-
-/// The file name of the sandbox receipt. This is available on iOS >= 8.0
-static NSString *const kFIRAIdentitySandboxReceiptFileName = @"sandboxReceipt";
-
-/// The following copyright from Landon J. Fuller applies to the isAppEncrypted function.
-///
-/// Copyright (c) 2017 Landon J. Fuller <landon@landonf.org>
-/// All rights reserved.
-///
-/// Permission is hereby granted, free of charge, to any person obtaining a copy of this software
-/// and associated documentation files (the "Software"), to deal in the Software without
-/// restriction, including without limitation the rights to use, copy, modify, merge, publish,
-/// distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the
-/// Software is furnished to do so, subject to the following conditions:
-///
-/// The above copyright notice and this permission notice shall be included in all copies or
-/// substantial portions of the Software.
-///
-/// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
-/// BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
-/// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
-/// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
-/// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
-///
-/// Comment from <a href="http://iphonedevwiki.net/index.php/Crack_prevention">iPhone Dev Wiki
-/// Crack Prevention</a>:
-/// App Store binaries are signed by both their developer and Apple. This encrypts the binary so
-/// that decryption keys are needed in order to make the binary readable. When iOS executes the
-/// binary, the decryption keys are used to decrypt the binary into a readable state where it is
-/// then loaded into memory and executed. iOS can tell the encryption status of a binary via the
-/// cryptid structure member of LC_ENCRYPTION_INFO MachO load command. If cryptid is a non-zero
-/// value then the binary is encrypted.
-///
-/// 'Cracking' works by letting the kernel decrypt the binary then siphoning the decrypted data into
-/// a new binary file, resigning, and repackaging. This will only work on jailbroken devices as
-/// codesignature validation has been removed. Resigning takes place because while the codesignature
-/// doesn't have to be valid thanks to the jailbreak, it does have to be in place unless you have
-/// AppSync or similar to disable codesignature checks.
-///
-/// More information at <a href="http://landonf.org/2009/02/index.html">Landon Fuller's blog</a>
-static BOOL isAppEncrypted() {
-  const struct mach_header *executableHeader = NULL;
-  for (uint32_t i = 0; i < _dyld_image_count(); i++) {
-    const struct mach_header *header = _dyld_get_image_header(i);
-    if (header && header->filetype == MH_EXECUTE) {
-      executableHeader = header;
-      break;
-    }
-  }
-
-  if (!executableHeader) {
-    return NO;
-  }
-
-  BOOL is64bit = (executableHeader->magic == MH_MAGIC_64);
-  uintptr_t cursor = (uintptr_t)executableHeader +
-                     (is64bit ? sizeof(struct mach_header_64) : sizeof(struct mach_header));
-  const struct segment_command *segmentCommand = NULL;
-  uint32_t i = 0;
-
-  while (i++ < executableHeader->ncmds) {
-    segmentCommand = (struct segment_command *)cursor;
-
-    if (!segmentCommand) {
-      continue;
-    }
-
-    if ((!is64bit && segmentCommand->cmd == LC_ENCRYPTION_INFO) ||
-        (is64bit && segmentCommand->cmd == LC_ENCRYPTION_INFO_64)) {
-      if (is64bit) {
-        struct encryption_info_command_64 *cryptCmd =
-            (struct encryption_info_command_64 *)segmentCommand;
-        return cryptCmd && cryptCmd->cryptid != 0;
-      } else {
-        struct encryption_info_command *cryptCmd = (struct encryption_info_command *)segmentCommand;
-        return cryptCmd && cryptCmd->cryptid != 0;
-      }
-    }
-    cursor += segmentCommand->cmdsize;
-  }
-
-  return NO;
-}
-
-+ (BOOL)isFromAppStore {
-  static dispatch_once_t isEncryptedOnce;
-  static BOOL isEncrypted = NO;
-
-  dispatch_once(&isEncryptedOnce, ^{
-    isEncrypted = isAppEncrypted();
-  });
-
-  if ([FIRAppEnvironmentUtil isSimulator]) {
-    return NO;
-  }
-
-  // If an app contain the sandboxReceipt file, it means its coming from TestFlight
-  // This must be checked before the SCInfo Folder check below since TestFlight apps may
-  // also have an SCInfo folder.
-  if ([FIRAppEnvironmentUtil isAppStoreReceiptSandbox]) {
-    return NO;
-  }
-
-  if ([FIRAppEnvironmentUtil hasSCInfoFolder]) {
-    // When iTunes downloads a .ipa, it also gets a customized .sinf file which is added to the
-    // main SC_Info directory.
-    return YES;
-  }
-
-  // For iOS >= 8.0, iTunesMetadata.plist is moved outside of the sandbox. Any attempt to read
-  // the iTunesMetadata.plist outside of the sandbox will be rejected by Apple.
-  // If the app does not contain the embedded.mobileprovision which is stripped out by Apple when
-  // the app is submitted to store, then it is highly likely that it is from Apple Store.
-  return isEncrypted && ![FIRAppEnvironmentUtil hasEmbeddedMobileProvision];
-}
-
-+ (BOOL)isAppStoreReceiptSandbox {
-  // Since checking the App Store's receipt URL can be memory intensive, check the option in the
-  // Info.plist if developers opted out of this check.
-  id enableSandboxCheck =
-      [[NSBundle mainBundle] objectForInfoDictionaryKey:kFIRAppStoreReceiptURLCheckEnabledKey];
-  if (enableSandboxCheck && [enableSandboxCheck isKindOfClass:[NSNumber class]] &&
-      ![enableSandboxCheck boolValue]) {
-    return NO;
-  }
-
-  NSURL *appStoreReceiptURL = [NSBundle mainBundle].appStoreReceiptURL;
-  NSString *appStoreReceiptFileName = appStoreReceiptURL.lastPathComponent;
-  return [appStoreReceiptFileName isEqualToString:kFIRAIdentitySandboxReceiptFileName];
-}
-
-+ (BOOL)hasEmbeddedMobileProvision {
-#if TARGET_OS_IOS || TARGET_OS_TV
-  return [[NSBundle mainBundle] pathForResource:@"embedded" ofType:@"mobileprovision"].length > 0;
-#elif TARGET_OS_OSX
-  return NO;
-#endif
-}
-
-+ (BOOL)isSimulator {
-#if TARGET_OS_IOS || TARGET_OS_TV
-  NSString *platform = [FIRAppEnvironmentUtil deviceModel];
-  return [platform isEqual:@"x86_64"] || [platform isEqual:@"i386"];
-#elif TARGET_OS_OSX
-  return NO;
-#endif
-}
-
-+ (NSString *)deviceModel {
-  static dispatch_once_t once;
-  static NSString *deviceModel;
-
-  dispatch_once(&once, ^{
-    struct utsname systemInfo;
-    if (uname(&systemInfo) == 0) {
-      deviceModel = [NSString stringWithUTF8String:systemInfo.machine];
-    }
-  });
-  return deviceModel;
-}
-
-+ (NSString *)systemVersion {
-  // Assemble the systemVersion, excluding the patch version if it's 0.
-  NSOperatingSystemVersion osVersion = [NSProcessInfo processInfo].operatingSystemVersion;
-  NSMutableString *versionString = [[NSMutableString alloc]
-      initWithFormat:@"%ld.%ld", (long)osVersion.majorVersion, (long)osVersion.minorVersion];
-  if (osVersion.patchVersion != 0) {
-    [versionString appendFormat:@".%ld", (long)osVersion.patchVersion];
-  }
-
-  return versionString;
-}
-
-+ (BOOL)isAppExtension {
-#if TARGET_OS_IOS || TARGET_OS_TV
-  // Documented by <a href="https://goo.gl/RRB2Up">Apple</a>
-  BOOL appExtension = [[[NSBundle mainBundle] bundlePath] hasSuffix:@".appex"];
-  return appExtension;
-#elif TARGET_OS_OSX
-  return NO;
-#endif
-}
-
-#pragma mark - Helper methods
-
-+ (BOOL)hasSCInfoFolder {
-#if TARGET_OS_IOS || TARGET_OS_TV
-  NSString *bundlePath = [NSBundle mainBundle].bundlePath;
-  NSString *scInfoPath = [bundlePath stringByAppendingPathComponent:@"SC_Info"];
-  return [[NSFileManager defaultManager] fileExistsAtPath:scInfoPath];
-#elif TARGET_OS_OSX
-  return NO;
-#endif
-}
-
-@end