10 files changed, 0 insertions, 1561 deletions

diff --git a/Firebase/Utilities/Network/GULMutableDictionary.m b/Firebase/Utilities/Network/GULMutableDictionary.m
deleted file mode 100644
index d281eb4..0000000
--- a/Firebase/Utilities/Network/GULMutableDictionary.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/GULMutableDictionary.h"
-
-@implementation GULMutableDictionary {
-  /// 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("GULMutableDictionary", 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/Utilities/Network/GULNetwork.m b/Firebase/Utilities/Network/GULNetwork.m
deleted file mode 100644
index 233500b..0000000
--- a/Firebase/Utilities/Network/GULNetwork.m
+++ /dev/null
@@ -1,388 +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/GULNetwork.h"
-#import "Private/GULNetworkMessageCode.h"
-
-#import <GoogleUtilities/GULLogger.h>
-#import <GoogleUtilities/GULNSData+zlib.h>
-#import <GoogleUtilities/GULReachabilityChecker.h>
-#import "Private/GULMutableDictionary.h"
-#import "Private/GULNetworkConstants.h"
-
-/// Constant string for request header Content-Encoding.
-static NSString *const kGULNetworkContentCompressionKey = @"Content-Encoding";
-
-/// Constant string for request header Content-Encoding value.
-static NSString *const kGULNetworkContentCompressionValue = @"gzip";
-
-/// Constant string for request header Content-Length.
-static NSString *const kGULNetworkContentLengthKey = @"Content-Length";
-
-/// Constant string for request header Content-Type.
-static NSString *const kGULNetworkContentTypeKey = @"Content-Type";
-
-/// Constant string for request header Content-Type value.
-static NSString *const kGULNetworkContentTypeValue = @"application/x-www-form-urlencoded";
-
-/// Constant string for GET request method.
-static NSString *const kGULNetworkGETRequestMethod = @"GET";
-
-/// Constant string for POST request method.
-static NSString *const kGULNetworkPOSTRequestMethod = @"POST";
-
-/// Default constant string as a prefix for network logger.
-static NSString *const kGULNetworkLogTag = @"Google/Utilities/Network";
-
-@interface GULNetwork () <GULReachabilityDelegate, GULNetworkLoggerDelegate>
-@end
-
-@implementation GULNetwork {
-  /// Network reachability.
-  GULReachabilityChecker *_reachability;
-
-  /// The dictionary of requests by session IDs { NSString : id }.
-  GULMutableDictionary *_requests;
-}
-
-- (instancetype)init {
-  return [self initWithReachabilityHost:kGULNetworkReachabilityHost];
-}
-
-- (instancetype)initWithReachabilityHost:(NSString *)reachabilityHost {
-  self = [super init];
-  if (self) {
-    // Setup reachability.
-    _reachability = [[GULReachabilityChecker alloc] initWithReachabilityDelegate:self
-                                                                        withHost:reachabilityHost];
-    if (![_reachability start]) {
-      return nil;
-    }
-
-    _requests = [[GULMutableDictionary alloc] init];
-    _timeoutInterval = kGULNetworkTimeOutInterval;
-  }
-  return self;
-}
-
-- (void)dealloc {
-  _reachability.reachabilityDelegate = nil;
-  [_reachability stop];
-}
-
-#pragma mark - External Methods
-
-+ (void)handleEventsForBackgroundURLSessionID:(NSString *)sessionID
-                            completionHandler:(GULNetworkSystemCompletionHandler)completionHandler {
-  [GULNetworkURLSession handleEventsForBackgroundURLSessionID:sessionID
-                                            completionHandler:completionHandler];
-}
-
-- (NSString *)postURL:(NSURL *)url
-                   payload:(NSData *)payload
-                     queue:(dispatch_queue_t)queue
-    usingBackgroundSession:(BOOL)usingBackgroundSession
-         completionHandler:(GULNetworkCompletionHandler)handler {
-  if (!url.absoluteString.length) {
-    [self handleErrorWithCode:GULErrorCodeNetworkInvalidURL queue:queue withHandler:handler];
-    return nil;
-  }
-
-  NSTimeInterval timeOutInterval = _timeoutInterval ?: kGULNetworkTimeOutInterval;
-
-  NSMutableURLRequest *request =
-      [[NSMutableURLRequest alloc] initWithURL:url
-                                   cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
-                               timeoutInterval:timeOutInterval];
-
-  if (!request) {
-    [self handleErrorWithCode:GULErrorCodeNetworkSessionTaskCreation
-                        queue:queue
-                  withHandler:handler];
-    return nil;
-  }
-
-  NSError *compressError = nil;
-  NSData *compressedData = [NSData gul_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:GULErrorCodeNetworkPayloadCompression
-                          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:kGULNetworkContentLengthKey];
-  request.HTTPBody = compressedData;
-  request.HTTPMethod = kGULNetworkPOSTRequestMethod;
-  [request setValue:kGULNetworkContentTypeValue forHTTPHeaderField:kGULNetworkContentTypeKey];
-  [request setValue:kGULNetworkContentCompressionValue
-      forHTTPHeaderField:kGULNetworkContentCompressionKey];
-
-  GULNetworkURLSession *fetcher = [[GULNetworkURLSession alloc] initWithNetworkLoggerDelegate:self];
-  fetcher.backgroundNetworkEnabled = usingBackgroundSession;
-
-  __weak GULNetwork *weakSelf = self;
-  NSString *requestID = [fetcher
-      sessionIDFromAsyncPOSTRequest:request
-                  completionHandler:^(NSHTTPURLResponse *response, NSData *data,
-                                      NSString *sessionID, NSError *error) {
-                    GULNetwork *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:GULErrorCodeNetworkSessionTaskCreation
-                        queue:queue
-                  withHandler:handler];
-    return nil;
-  }
-
-  [self GULNetwork_logWithLevel:kGULNetworkLogLevelDebug
-                    messageCode:kGULNetworkMessageCodeNetwork000
-                        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:(GULNetworkCompletionHandler)handler {
-  if (!url.absoluteString.length) {
-    [self handleErrorWithCode:GULErrorCodeNetworkInvalidURL queue:queue withHandler:handler];
-    return nil;
-  }
-
-  NSTimeInterval timeOutInterval = _timeoutInterval ?: kGULNetworkTimeOutInterval;
-  NSMutableURLRequest *request =
-      [[NSMutableURLRequest alloc] initWithURL:url
-                                   cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
-                               timeoutInterval:timeOutInterval];
-
-  if (!request) {
-    [self handleErrorWithCode:GULErrorCodeNetworkSessionTaskCreation
-                        queue:queue
-                  withHandler:handler];
-    return nil;
-  }
-
-  request.HTTPMethod = kGULNetworkGETRequestMethod;
-  request.allHTTPHeaderFields = headers;
-
-  GULNetworkURLSession *fetcher = [[GULNetworkURLSession alloc] initWithNetworkLoggerDelegate:self];
-  fetcher.backgroundNetworkEnabled = usingBackgroundSession;
-
-  __weak GULNetwork *weakSelf = self;
-  NSString *requestID = [fetcher
-      sessionIDFromAsyncGETRequest:request
-                 completionHandler:^(NSHTTPURLResponse *response, NSData *data, NSString *sessionID,
-                                     NSError *error) {
-                   GULNetwork *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:GULErrorCodeNetworkSessionTaskCreation
-                        queue:queue
-                  withHandler:handler];
-    return nil;
-  }
-
-  [self GULNetwork_logWithLevel:kGULNetworkLogLevelDebug
-                    messageCode:kGULNetworkMessageCodeNetwork001
-                        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:(GULReachabilityChecker *)reachability
-       statusChanged:(GULReachabilityStatus)status {
-  _networkConnected = (status == kGULReachabilityViaCellular || status == kGULReachabilityViaWifi);
-  [_reachabilityDelegate reachabilityDidChange];
-}
-
-#pragma mark - Network logger delegate
-
-- (void)setLoggerDelegate:(id<GULNetworkLoggerDelegate>)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(GULNetwork_logWithLevel:messageCode:message:contexts:)] ||
-      ![loggerDelegate
-          respondsToSelector:@selector(GULNetwork_logWithLevel:messageCode:message:context:)] ||
-      !
-      [loggerDelegate respondsToSelector:@selector(GULNetwork_logWithLevel:messageCode:message:)]) {
-    GULLogError(kGULLoggerNetwork, NO,
-                [NSString stringWithFormat:@"I-NET%06ld", (long)kGULNetworkMessageCodeNetwork002],
-                @"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:(GULNetworkCompletionHandler)handler {
-  NSDictionary *userInfo = @{kGULNetworkErrorContext : @"Failed to create network request"};
-  NSError *error =
-      [[NSError alloc] initWithDomain:kGULNetworkErrorDomain code:code userInfo:userInfo];
-  [self GULNetwork_logWithLevel:kGULNetworkLogLevelWarning
-                    messageCode:kGULNetworkMessageCodeNetwork002
-                        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)GULNetwork_logWithLevel:(GULNetworkLogLevel)logLevel
-                    messageCode:(GULNetworkMessageCode)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 GULNetwork_logWithLevel:logLevel
-                                 messageCode:messageCode
-                                     message:message
-                                    contexts:contexts];
-    return;
-  }
-  if (_isDebugModeEnabled || logLevel == kGULNetworkLogLevelError ||
-      logLevel == kGULNetworkLogLevelWarning || logLevel == kGULNetworkLogLevelInfo) {
-    NSString *formattedMessage = GULStringWithLogMessage(message, logLevel, contexts);
-    NSLog(@"%@", formattedMessage);
-    GULLogBasic((GULLoggerLevel)logLevel, kGULLoggerNetwork, NO,
-                [NSString stringWithFormat:@"I-NET%06ld", (long)messageCode], formattedMessage,
-                NULL);
-  }
-}
-
-- (void)GULNetwork_logWithLevel:(GULNetworkLogLevel)logLevel
-                    messageCode:(GULNetworkMessageCode)messageCode
-                        message:(NSString *)message
-                        context:(id)context {
-  if (_loggerDelegate) {
-    [_loggerDelegate GULNetwork_logWithLevel:logLevel
-                                 messageCode:messageCode
-                                     message:message
-                                     context:context];
-    return;
-  }
-  NSArray *contexts = context ? @[ context ] : @[];
-  [self GULNetwork_logWithLevel:logLevel messageCode:messageCode message:message contexts:contexts];
-}
-
-- (void)GULNetwork_logWithLevel:(GULNetworkLogLevel)logLevel
-                    messageCode:(GULNetworkMessageCode)messageCode
-                        message:(NSString *)message {
-  if (_loggerDelegate) {
-    [_loggerDelegate GULNetwork_logWithLevel:logLevel messageCode:messageCode message:message];
-    return;
-  }
-  [self GULNetwork_logWithLevel:logLevel messageCode:messageCode message:message contexts:@[]];
-}
-
-/// Returns a string for the given log level (e.g. kGULNetworkLogLevelError -> @"ERROR").
-static NSString *GULLogLevelDescriptionFromLogLevel(GULNetworkLogLevel logLevel) {
-  static NSDictionary *levelNames = nil;
-  static dispatch_once_t onceToken;
-  dispatch_once(&onceToken, ^{
-    levelNames = @{
-      @(kGULNetworkLogLevelError) : @"ERROR",
-      @(kGULNetworkLogLevelWarning) : @"WARNING",
-      @(kGULNetworkLogLevelInfo) : @"INFO",
-      @(kGULNetworkLogLevelDebug) : @"DEBUG"
-    };
-  });
-  return levelNames[@(logLevel)];
-}
-
-/// Returns a formatted string to be used for console logging.
-static NSString *GULStringWithLogMessage(NSString *message,
-                                         GULNetworkLogLevel logLevel,
-                                         NSArray *contexts) {
-  if (!message) {
-    message = @"(Message was nil)";
-  } else if (!message.length) {
-    message = @"(Message was empty)";
-  }
-  NSMutableString *result = [[NSMutableString alloc]
-      initWithFormat:@"<%@/%@> %@", kGULNetworkLogTag, GULLogLevelDescriptionFromLogLevel(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/Utilities/Network/GULNetworkConstants.m b/Firebase/Utilities/Network/GULNetworkConstants.m
deleted file mode 100644
index 90bd03d..0000000
--- a/Firebase/Utilities/Network/GULNetworkConstants.m
+++ /dev/null
@@ -1,40 +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/GULNetworkConstants.h"
-
-#import <Foundation/Foundation.h>
-
-NSString *const kGULNetworkBackgroundSessionConfigIDPrefix = @"com.gul.network.background-upload";
-NSString *const kGULNetworkApplicationSupportSubdirectory = @"GUL/Network";
-NSString *const kGULNetworkTempDirectoryName = @"GULNetworkTemporaryDirectory";
-const NSTimeInterval kGULNetworkTempFolderExpireTime = 60 * 60;  // 1 hour
-const NSTimeInterval kGULNetworkTimeOutInterval = 60;            // 1 minute.
-NSString *const kGULNetworkReachabilityHost = @"app-measurement.com";
-NSString *const kGULNetworkErrorContext = @"Context";
-
-const int kGULNetworkHTTPStatusOK = 200;
-const int kGULNetworkHTTPStatusNoContent = 204;
-const int kGULNetworkHTTPStatusCodeMultipleChoices = 300;
-const int kGULNetworkHTTPStatusCodeMovedPermanently = 301;
-const int kGULNetworkHTTPStatusCodeFound = 302;
-const int kGULNetworkHTTPStatusCodeNotModified = 304;
-const int kGULNetworkHTTPStatusCodeMovedTemporarily = 307;
-const int kGULNetworkHTTPStatusCodeNotFound = 404;
-const int kGULNetworkHTTPStatusCodeCannotAcceptTraffic = 429;
-const int kGULNetworkHTTPStatusCodeUnavailable = 503;
-
-NSString *const kGULNetworkErrorDomain = @"com.gul.network.ErrorDomain";
-
-GULLoggerService kGULLoggerNetwork = @"[GULNetwork]";
diff --git a/Firebase/Utilities/Network/GULNetworkURLSession.m b/Firebase/Utilities/Network/GULNetworkURLSession.m
deleted file mode 100644
index cb8a204..0000000
--- a/Firebase/Utilities/Network/GULNetworkURLSession.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/GULNetworkURLSession.h"
-
-#import <GoogleUtilities/GULLogger.h>
-#import "Private/GULMutableDictionary.h"
-#import "Private/GULNetworkConstants.h"
-#import "Private/GULNetworkMessageCode.h"
-
-@implementation GULNetworkURLSession {
-  /// The handler to be called when the request completes or error has occurs.
-  GULNetworkURLSessionCompletionHandler _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<GULNetworkLoggerDelegate>)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, kGULNetworkApplicationSupportSubdirectory,
-      kGULNetworkTempDirectoryName
-    ];
-    _networkDirectoryURL = [NSURL fileURLWithPathComponents:tempPathComponents];
-    _sessionID = [NSString stringWithFormat:@"%@-%@", kGULNetworkBackgroundSessionConfigIDPrefix,
-                                            [[NSUUID UUID] UUIDString]];
-    _loggerDelegate = networkLoggerDelegate;
-  }
-  return self;
-}
-
-#pragma mark - External Methods
-
-#pragma mark - To be called from AppDelegate
-
-+ (void)handleEventsForBackgroundURLSessionID:(NSString *)sessionID
-                            completionHandler:
-                                (GULNetworkSystemCompletionHandler)systemCompletionHandler {
-  // The session may not be Analytics background. Ignore those that do not have the prefix.
-  if (![sessionID hasPrefix:kGULNetworkBackgroundSessionConfigIDPrefix]) {
-    return;
-  }
-  GULNetworkURLSession *fetcher = [self fetcherWithSessionIdentifier:sessionID];
-  if (fetcher != nil) {
-    [fetcher addSystemCompletionHandler:systemCompletionHandler forSession:sessionID];
-  } else {
-    GULLogError(kGULLoggerNetwork, NO,
-                [NSString stringWithFormat:@"I-NET%06ld", (long)kGULNetworkMessageCodeNetwork003],
-                @"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:(GULNetworkURLSessionCompletionHandler)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:kGULNetworkTempFolderExpireTime];
-
-  // 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 GULNetwork_logWithLevel:kGULNetworkLogLevelError
-                                   messageCode:kGULNetworkMessageCodeURLSession000
-                                       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:kGULNetworkErrorDomain
-                  code:GULErrorCodeNetworkRequestCreation
-              userInfo:@{kGULNetworkErrorContext : @"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:(GULNetworkURLSessionCompletionHandler)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:kGULNetworkErrorDomain
-                  code:GULErrorCodeNetworkRequestCreation
-              userInfo:@{kGULNetworkErrorContext : @"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
-        GULNetwork_logWithLevel:kGULNetworkLogLevelError
-                    messageCode:kGULNetworkMessageCodeURLSession001
-                        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 GULNetwork_logWithLevel:kGULNetworkLogLevelError
-                                 messageCode:kGULNetworkMessageCodeURLSession002
-                                     message:@"Cannot read the content of downloaded data"
-                                     context:error];
-    _downloadedData = nil;
-  }
-}
-
-#if TARGET_OS_IOS || TARGET_OS_TV
-- (void)URLSessionDidFinishEventsForBackgroundURLSession:(NSURLSession *)session {
-  [_loggerDelegate GULNetwork_logWithLevel:kGULNetworkLogLevelDebug
-                               messageCode:kGULNetworkMessageCodeURLSession003
-                                   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.
-  GULNetworkURLSessionCompletionHandler 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:kGULNetworkErrorDomain
-                  code:GULErrorCodeNetworkInvalidResponse
-              userInfo:@{kGULNetworkErrorContext : @"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:kGULNetworkTempFolderExpireTime];
-}
-
-- (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 GULNetwork_logWithLevel:kGULNetworkLogLevelDebug
-                                   messageCode:kGULNetworkMessageCodeURLSession004
-                                       message:@"Received empty server trust for host. Host"
-                                       context:_request.URL];
-      completionHandler(NSURLSessionAuthChallengePerformDefaultHandling, nil);
-      return;
-    }
-    NSURLCredential *credential = [NSURLCredential credentialForTrust:serverTrust];
-    if (!credential) {
-      [_loggerDelegate GULNetwork_logWithLevel:kGULNetworkLogLevelWarning
-                                   messageCode:kGULNetworkMessageCodeURLSession005
-                                       message:@"Unable to verify server identity. Host"
-                                       context:_request.URL];
-      completionHandler(NSURLSessionAuthChallengeCancelAuthenticationChallenge, nil);
-      return;
-    }
-
-    [_loggerDelegate GULNetwork_logWithLevel:kGULNetworkLogLevelDebug
-                                 messageCode:kGULNetworkMessageCodeURLSession006
-                                     message:@"Received SSL challenge for host. Host"
-                                     context:_request.URL];
-
-    void (^callback)(BOOL) = ^(BOOL allow) {
-      if (allow) {
-        completionHandler(NSURLSessionAuthChallengeUseCredential, credential);
-      } else {
-        [self->_loggerDelegate
-            GULNetwork_logWithLevel:kGULNetworkLogLevelDebug
-                        messageCode:kGULNetworkMessageCodeURLSession007
-                            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([GULNetworkURLSession class]) {
-        trustError = SecTrustEvaluate(serverTrust, &trustEval);
-      }
-
-      if (trustError != errSecSuccess) {
-        [self->_loggerDelegate GULNetwork_logWithLevel:kGULNetworkLogLevelError
-                                           messageCode:kGULNetworkMessageCodeURLSession008
-                                               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:(GULNetworkSystemCompletionHandler)handler
-                        forSession:(NSString *)identifier {
-  if (!handler) {
-    [_loggerDelegate
-        GULNetwork_logWithLevel:kGULNetworkLogLevelError
-                    messageCode:kGULNetworkMessageCodeURLSession009
-                        message:@"Cannot store nil system completion handler in network"];
-    return;
-  }
-
-  if (!identifier.length) {
-    [_loggerDelegate
-        GULNetwork_logWithLevel:kGULNetworkLogLevelError
-                    messageCode:kGULNetworkMessageCodeURLSession010
-                        message:
-                            @"Cannot store system completion handler with empty network "
-                             "session identifier"];
-    return;
-  }
-
-  GULMutableDictionary *systemCompletionHandlers =
-      [[self class] sessionIDToSystemCompletionHandlerDictionary];
-  if (systemCompletionHandlers[identifier]) {
-    [_loggerDelegate GULNetwork_logWithLevel:kGULNetworkLogLevelWarning
-                                 messageCode:kGULNetworkMessageCodeURLSession011
-                                     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 {
-  GULMutableDictionary *systemCompletionHandlers =
-      [[self class] sessionIDToSystemCompletionHandlerDictionary];
-  GULNetworkSystemCompletionHandler 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
-        GULNetwork_logWithLevel:kGULNetworkLogLevelDebug
-                    messageCode:kGULNetworkMessageCodeURLSession012
-                        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
-        GULNetwork_logWithLevel:kGULNetworkLogLevelError
-                    messageCode:kGULNetworkMessageCodeURLSession013
-                        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];
-  GULNetworkURLSession *session = [sessionIdentifierToFetcherMap objectForKey:sessionIdentifier];
-  if (!session && [sessionIdentifier hasPrefix:kGULNetworkBackgroundSessionConfigIDPrefix]) {
-    session = [[GULNetworkURLSession 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.
-+ (GULMutableDictionary *)sessionIDToSystemCompletionHandlerDictionary {
-  static GULMutableDictionary *systemCompletionHandlers;
-
-  static dispatch_once_t systemCompletionHandlerOnceToken;
-  dispatch_once(&systemCompletionHandlerOnceToken, ^{
-    systemCompletionHandlers = [[GULMutableDictionary alloc] init];
-  });
-  return systemCompletionHandlers;
-}
-
-- (NSURL *)temporaryFilePathWithSessionID:(NSString *)sessionID {
-  NSString *tempName = [NSString stringWithFormat:@"GULUpload_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
-        GULNetwork_logWithLevel:kGULNetworkLogLevelWarning
-                    messageCode:kGULNetworkMessageCodeURLSession014
-                        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 GULNetwork_logWithLevel:kGULNetworkLogLevelError
-                                 messageCode:kGULNetworkMessageCodeURLSession015
-                                     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 GULNetwork_logWithLevel:kGULNetworkLogLevelError
-                                 messageCode:kGULNetworkMessageCodeURLSession016
-                                     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 = @[
-    @(kGULNetworkHTTPStatusCodeFound), @(kGULNetworkHTTPStatusCodeMovedPermanently),
-    @(kGULNetworkHTTPStatusCodeMovedTemporarily), @(kGULNetworkHTTPStatusCodeMultipleChoices)
-  ];
-
-  // 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:(GULNetworkURLSessionCompletionHandler)handler
-                 withResponse:(NSHTTPURLResponse *)response
-                         data:(NSData *)data
-                        error:(NSError *)error {
-  if (error) {
-    [_loggerDelegate GULNetwork_logWithLevel:kGULNetworkLogLevelError
-                                 messageCode:kGULNetworkMessageCodeURLSession017
-                                     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/Utilities/Network/Private/GULMutableDictionary.h b/Firebase/Utilities/Network/Private/GULMutableDictionary.h
deleted file mode 100644
index a8cc45b..0000000
--- a/Firebase/Utilities/Network/Private/GULMutableDictionary.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 GULMutableDictionary : 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/Utilities/Network/Private/GULNetwork.h b/Firebase/Utilities/Network/Private/GULNetwork.h
deleted file mode 100644
index 0e75ae5..0000000
--- a/Firebase/Utilities/Network/Private/GULNetwork.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 "GULNetworkConstants.h"
-#import "GULNetworkLoggerProtocol.h"
-#import "GULNetworkURLSession.h"
-
-/// Delegate protocol for GULNetwork events.
-@protocol GULNetworkReachabilityDelegate
-
-/// 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 GULNetwork : 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<GULNetworkReachabilityDelegate> reachabilityDelegate;
-
-/// An optional delegate that can be used to log messages, warnings or errors that occur in the
-/// network operations.
-@property(nonatomic, weak) id<GULNetworkLoggerDelegate> 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:(GULNetworkSystemCompletionHandler)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:(GULNetworkCompletionHandler)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:(GULNetworkCompletionHandler)handler;
-
-@end
diff --git a/Firebase/Utilities/Network/Private/GULNetworkConstants.h b/Firebase/Utilities/Network/Private/GULNetworkConstants.h
deleted file mode 100644
index 44d440b..0000000
--- a/Firebase/Utilities/Network/Private/GULNetworkConstants.h
+++ /dev/null
@@ -1,79 +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 <GoogleUtilities/GULLogger.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, GULNetworkErrorCode) {
-  /// Unknown error.
-  GULNetworkErrorCodeUnknown = 0,
-  /// Error occurs when the request URL is invalid.
-  GULErrorCodeNetworkInvalidURL = 1,
-  /// Error occurs when request cannot be constructed.
-  GULErrorCodeNetworkRequestCreation = 2,
-  /// Error occurs when payload cannot be compressed.
-  GULErrorCodeNetworkPayloadCompression = 3,
-  /// Error occurs when session task cannot be created.
-  GULErrorCodeNetworkSessionTaskCreation = 4,
-  /// Error occurs when there is no response.
-  GULErrorCodeNetworkInvalidResponse = 5
-};
-
-#pragma mark - Network constants
-
-/// The prefix of the ID of the background session.
-extern NSString *const kGULNetworkBackgroundSessionConfigIDPrefix;
-
-/// The sub directory to store the files of data that is being uploaded in the background.
-extern NSString *const kGULNetworkApplicationSupportSubdirectory;
-
-/// Name of the temporary directory that stores files for background uploading.
-extern NSString *const kGULNetworkTempDirectoryName;
-
-/// The period when the temporary uploading file can stay.
-extern const NSTimeInterval kGULNetworkTempFolderExpireTime;
-
-/// The default network request timeout interval.
-extern const NSTimeInterval kGULNetworkTimeOutInterval;
-
-/// The host to check the reachability of the network.
-extern NSString *const kGULNetworkReachabilityHost;
-
-/// The key to get the error context of the UserInfo.
-extern NSString *const kGULNetworkErrorContext;
-
-#pragma mark - Network Status Code
-
-extern const int kGULNetworkHTTPStatusOK;
-extern const int kGULNetworkHTTPStatusNoContent;
-extern const int kGULNetworkHTTPStatusCodeMultipleChoices;
-extern const int kGULNetworkHTTPStatusCodeMovedPermanently;
-extern const int kGULNetworkHTTPStatusCodeFound;
-extern const int kGULNetworkHTTPStatusCodeNotModified;
-extern const int kGULNetworkHTTPStatusCodeMovedTemporarily;
-extern const int kGULNetworkHTTPStatusCodeNotFound;
-extern const int kGULNetworkHTTPStatusCodeCannotAcceptTraffic;
-extern const int kGULNetworkHTTPStatusCodeUnavailable;
-
-#pragma mark - Error Domain
-
-extern NSString *const kGULNetworkErrorDomain;
-
-/// The logger service for GULNetwork.
-extern GULLoggerService kGULLoggerNetwork;
diff --git a/Firebase/Utilities/Network/Private/GULNetworkLoggerProtocol.h b/Firebase/Utilities/Network/Private/GULNetworkLoggerProtocol.h
deleted file mode 100644
index f1be590..0000000
--- a/Firebase/Utilities/Network/Private/GULNetworkLoggerProtocol.h
+++ /dev/null
@@ -1,51 +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 <GoogleUtilities/GULLoggerLevel.h>
-
-#import "GULNetworkMessageCode.h"
-
-/// The log levels used by GULNetworkLogger.
-typedef NS_ENUM(NSInteger, GULNetworkLogLevel) {
-  kGULNetworkLogLevelError = GULLoggerLevelError,
-  kGULNetworkLogLevelWarning = GULLoggerLevelWarning,
-  kGULNetworkLogLevelInfo = GULLoggerLevelInfo,
-  kGULNetworkLogLevelDebug = GULLoggerLevelDebug,
-};
-
-@protocol GULNetworkLoggerDelegate <NSObject>
-
-@required
-/// Tells the delegate to log a message with an array of contexts and the log level.
-- (void)GULNetwork_logWithLevel:(GULNetworkLogLevel)logLevel
-                    messageCode:(GULNetworkMessageCode)messageCode
-                        message:(NSString *)message
-                       contexts:(NSArray *)contexts;
-
-/// Tells the delegate to log a message with a context and the log level.
-- (void)GULNetwork_logWithLevel:(GULNetworkLogLevel)logLevel
-                    messageCode:(GULNetworkMessageCode)messageCode
-                        message:(NSString *)message
-                        context:(id)context;
-
-/// Tells the delegate to log a message with the log level.
-- (void)GULNetwork_logWithLevel:(GULNetworkLogLevel)logLevel
-                    messageCode:(GULNetworkMessageCode)messageCode
-                        message:(NSString *)message;
-
-@end
diff --git a/Firebase/Utilities/Network/Private/GULNetworkMessageCode.h b/Firebase/Utilities/Network/Private/GULNetworkMessageCode.h
deleted file mode 100644
index ce78e60..0000000
--- a/Firebase/Utilities/Network/Private/GULNetworkMessageCode.h
+++ /dev/null
@@ -1,44 +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, GULNetworkMessageCode) {
-  // GULNetwork.m
-  kGULNetworkMessageCodeNetwork000 = 900000,  // I-NET900000
-  kGULNetworkMessageCodeNetwork001 = 900001,  // I-NET900001
-  kGULNetworkMessageCodeNetwork002 = 900002,  // I-NET900002
-  kGULNetworkMessageCodeNetwork003 = 900003,  // I-NET900003
-  // GULNetworkURLSession.m
-  kGULNetworkMessageCodeURLSession000 = 901000,  // I-NET901000
-  kGULNetworkMessageCodeURLSession001 = 901001,  // I-NET901001
-  kGULNetworkMessageCodeURLSession002 = 901002,  // I-NET901002
-  kGULNetworkMessageCodeURLSession003 = 901003,  // I-NET901003
-  kGULNetworkMessageCodeURLSession004 = 901004,  // I-NET901004
-  kGULNetworkMessageCodeURLSession005 = 901005,  // I-NET901005
-  kGULNetworkMessageCodeURLSession006 = 901006,  // I-NET901006
-  kGULNetworkMessageCodeURLSession007 = 901007,  // I-NET901007
-  kGULNetworkMessageCodeURLSession008 = 901008,  // I-NET901008
-  kGULNetworkMessageCodeURLSession009 = 901009,  // I-NET901009
-  kGULNetworkMessageCodeURLSession010 = 901010,  // I-NET901010
-  kGULNetworkMessageCodeURLSession011 = 901011,  // I-NET901011
-  kGULNetworkMessageCodeURLSession012 = 901012,  // I-NET901012
-  kGULNetworkMessageCodeURLSession013 = 901013,  // I-NET901013
-  kGULNetworkMessageCodeURLSession014 = 901014,  // I-NET901014
-  kGULNetworkMessageCodeURLSession015 = 901015,  // I-NET901015
-  kGULNetworkMessageCodeURLSession016 = 901016,  // I-NET901016
-  kGULNetworkMessageCodeURLSession017 = 901017,  // I-NET901017
-  kGULNetworkMessageCodeURLSession018 = 901018,  // I-NET901018
-};
diff --git a/Firebase/Utilities/Network/Private/GULNetworkURLSession.h b/Firebase/Utilities/Network/Private/GULNetworkURLSession.h
deleted file mode 100644
index 81190c6..0000000
--- a/Firebase/Utilities/Network/Private/GULNetworkURLSession.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 "GULNetworkLoggerProtocol.h"
-
-typedef void (^GULNetworkCompletionHandler)(NSHTTPURLResponse *response,
-                                            NSData *data,
-                                            NSError *error);
-typedef void (^GULNetworkURLSessionCompletionHandler)(NSHTTPURLResponse *response,
-                                                      NSData *data,
-                                                      NSString *sessionID,
-                                                      NSError *error);
-typedef void (^GULNetworkSystemCompletionHandler)(void);
-
-/// The protocol that uses NSURLSession for iOS >= 7.0 to handle requests and responses.
-@interface GULNetworkURLSession
-    : 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<GULNetworkLoggerDelegate> loggerDelegate;
-
-/// Calls the system provided completion handler after the background session is finished.
-+ (void)handleEventsForBackgroundURLSessionID:(NSString *)sessionID
-                            completionHandler:(GULNetworkSystemCompletionHandler)completionHandler;
-
-/// Initializes with logger delegate.
-- (instancetype)initWithNetworkLoggerDelegate:(id<GULNetworkLoggerDelegate>)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:(GULNetworkURLSessionCompletionHandler)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:(GULNetworkURLSessionCompletionHandler)handler;
-
-@end