Forwards app delegate's openURL invocations to `FIRAuth`. (#207)

5 files changed, 385 insertions, 22 deletions

diff --git a/Example/Auth/Tests/FIRAuthAppDelegateProxyTests.m b/Example/Auth/Tests/FIRAuthAppDelegateProxyTests.m
index 9ff7473..b65de93 100644
--- a/Example/Auth/Tests/FIRAuthAppDelegateProxyTests.m
+++ b/Example/Auth/Tests/FIRAuthAppDelegateProxyTests.m
@@ -33,7 +33,8 @@ NS_ASSUME_NONNULL_BEGIN
 
 /** @class FIRAuthLegacyAppDelegate
     @brief A @c UIApplicationDelegate implementation that implements
-        `application:didReceiveRemoteNotification:`.
+        `application:didReceiveRemoteNotification:` and
+        `application:openURL:sourceApplication:annotation:`.
  */
 @interface FIRAuthLegacyAppDelegate : NSObject <UIApplicationDelegate>
 
@@ -42,6 +43,11 @@ NS_ASSUME_NONNULL_BEGIN
  */
 @property(nonatomic, copy, nullable) NSDictionary *notificationReceived;
 
+/** @var urlOpened
+    @brief The last URL opened, if any.
+ */
+@property(nonatomic, copy, nullable) NSURL *urlOpened;
+
 @end
 
 @implementation FIRAuthLegacyAppDelegate
@@ -51,12 +57,21 @@ NS_ASSUME_NONNULL_BEGIN
   self.notificationReceived = userInfo;
 }
 
+- (BOOL)application:(UIApplication *)application
+              openURL:(NSURL *)url
+    sourceApplication:(nullable NSString *)sourceApplication
+           annotation:(id)annotation {
+  self.urlOpened = url;
+  return NO;
+}
+
 @end
 
 /** @class FIRAuthModernAppDelegate
     @brief A @c UIApplicationDelegate implementation that implements both
-        `application:didRegisterForRemoteNotificationsWithDeviceToken:` and
-        `application:didReceiveRemoteNotification:fetchCompletionHandler:`.
+        `application:didRegisterForRemoteNotificationsWithDeviceToken:`,
+        `application:didReceiveRemoteNotification:fetchCompletionHandler:`, and
+        `application:openURL:options:`.
  */
 @interface FIRAuthModernAppDelegate : NSObject <UIApplicationDelegate>
 
@@ -70,6 +85,11 @@ NS_ASSUME_NONNULL_BEGIN
  */
 @property(nonatomic, copy, nullable) NSDictionary *notificationReceived;
 
+/** @var urlOpened
+    @brief The last URL opened, if any.
+ */
+@property(nonatomic, copy, nullable) NSURL *urlOpened;
+
 @end
 
 @implementation FIRAuthModernAppDelegate
@@ -86,6 +106,34 @@ NS_ASSUME_NONNULL_BEGIN
   completionHandler(UIBackgroundFetchResultNewData);
 }
 
+- (BOOL)application:(UIApplication *)app
+            openURL:(NSURL *)url
+            options:(NSDictionary<UIApplicationOpenURLOptionsKey, id> *)options {
+  self.urlOpened = url;
+  return NO;
+}
+
+@end
+
+/** @class FIRAuthOtherLegacyAppDelegate
+    @brief A @c UIApplicationDelegate implementation that implements `application:handleOpenURL:`.
+ */
+@interface FIRAuthOtherLegacyAppDelegate : NSObject <UIApplicationDelegate>
+
+/** @var urlOpened
+    @brief The last URL opened, if any.
+ */
+@property(nonatomic, copy, nullable) NSURL *urlOpened;
+
+@end
+
+@implementation FIRAuthOtherLegacyAppDelegate
+
+- (BOOL)application:(UIApplication *)application handleOpenURL:(NSURL *)url {
+  self.urlOpened = url;
+  return NO;
+}
+
 @end
 
 /** @class FIRAuthAppDelegateProxyTests
@@ -108,6 +156,11 @@ NS_ASSUME_NONNULL_BEGIN
       @brief The fake notification for testing.
    */
   NSDictionary* _notification;
+
+  /** @var _url
+      @brief The fake URL for testing.
+   */
+  NSURL *_url;
 }
 
 - (void)setUp {
@@ -115,6 +168,7 @@ NS_ASSUME_NONNULL_BEGIN
   _mockApplication = OCMClassMock([UIApplication class]);
   _deviceToken = [@"asdf" dataUsingEncoding:NSUTF8StringEncoding];
   _notification = @{ @"zxcv" : @1234 };
+  _url = [NSURL URLWithString:@"https://abc.def/ghi"];
 }
 
 - (void)tearDown {
@@ -193,9 +247,23 @@ NS_ASSUME_NONNULL_BEGIN
         [[FIRAuthAppDelegateProxy alloc] initWithApplication:_mockApplication];
     XCTAssertNotNil(proxy);
 
-    // Verify `application:didReceiveRemoteNotification:` is not swizzled.
+    // Verify certain methods are swizzled while others are not.
+    XCTAssertTrue([delegate respondsToSelector:
+                   @selector(application:didRegisterForRemoteNotificationsWithDeviceToken:)]);
+    XCTAssertTrue([delegate respondsToSelector:
+                   @selector(application:didReceiveRemoteNotification:fetchCompletionHandler:)]);
     XCTAssertFalse([delegate respondsToSelector:
                     @selector(application:didReceiveRemoteNotification:)]);
+    if (&UIApplicationOpenURLOptionsAnnotationKey) {  // iOS 9+
+      XCTAssertTrue([delegate respondsToSelector:@selector(application:openURL:options:)]);
+      XCTAssertFalse([delegate respondsToSelector:
+                      @selector(application:openURL:sourceApplication:annotation:)]);
+    } else {
+      XCTAssertFalse([delegate respondsToSelector:@selector(application:openURL:options:)]);
+      XCTAssertTrue([delegate respondsToSelector:
+                     @selector(application:openURL:sourceApplication:annotation:)]);
+    }
+    XCTAssertFalse([delegate respondsToSelector:@selector(application:handleOpenURL:)]);
 
     // Verify the handler is called after being added.
     __weak id weakHandler;
@@ -203,13 +271,13 @@ NS_ASSUME_NONNULL_BEGIN
       id mockHandler = OCMProtocolMock(@protocol(FIRAuthAppDelegateHandler));
       [proxy addHandler:mockHandler];
 
-      // Verify handling of `application:didRegisterForRemoteNotificationsWithDeviceToken:`.
+      // Verify `application:didRegisterForRemoteNotificationsWithDeviceToken:` is handled.
       OCMExpect([mockHandler setAPNSToken:_deviceToken]);
       [delegate application:_mockApplication
           didRegisterForRemoteNotificationsWithDeviceToken:_deviceToken];
       OCMVerifyAll(mockHandler);
 
-      // Verify handling of `application:didReceiveRemoteNotification:fetchCompletionHandler:`.
+      // Verify `application:didReceiveRemoteNotification:fetchCompletionHandler:` is handled.
       OCMExpect([mockHandler canHandleNotification:_notification]).andReturn(YES);
       __block BOOL fetchCompletionHandlerCalled = NO;
       [delegate application:_mockApplication
@@ -221,6 +289,20 @@ NS_ASSUME_NONNULL_BEGIN
       OCMVerifyAll(mockHandler);
       XCTAssertTrue(fetchCompletionHandlerCalled);
 
+      // Verify one of the `application:openURL:...` methods is handled.
+      OCMExpect([mockHandler canHandleURL:_url]).andReturn(YES);
+      if (&UIApplicationOpenURLOptionsAnnotationKey) {  // iOS 9+
+        // Verify `application:openURL:options:` is handled.
+        XCTAssertTrue([delegate application:_mockApplication openURL:_url options:@{}]);
+      } else {
+        // Verify `application:openURL:sourceApplication:annotation:` is handled.
+        XCTAssertTrue([delegate application:_mockApplication
+                                    openURL:_url
+                          sourceApplication:@"sourceApplication"
+                                 annotation:@"annotaton"]);
+      }
+      OCMVerifyAll(mockHandler);
+
       weakHandler = mockHandler;
       XCTAssertNotNil(weakHandler);
     }
@@ -235,7 +317,14 @@ NS_ASSUME_NONNULL_BEGIN
               fetchCompletionHandler:^(UIBackgroundFetchResult result) {
       XCTFail(@"Should not call completion handler.");
     }];
-
+    if (&UIApplicationOpenURLOptionsAnnotationKey) {  // iOS 9+
+      XCTAssertFalse([delegate application:_mockApplication openURL:_url options:@{}]);
+    } else {
+      XCTAssertFalse([delegate application:_mockApplication
+                                   openURL:_url
+                         sourceApplication:@"sourceApplication"
+                                annotation:@"annotaton"]);
+    }
     weakProxy = proxy;
     XCTAssertNotNil(weakProxy);
   }
@@ -249,6 +338,14 @@ NS_ASSUME_NONNULL_BEGIN
             fetchCompletionHandler:^(UIBackgroundFetchResult result) {
     XCTFail(@"Should not call completion handler.");
   }];
+  if (&UIApplicationOpenURLOptionsAnnotationKey) {  // iOS 9+
+    XCTAssertFalse([delegate application:_mockApplication openURL:_url options:@{}]);
+  } else {
+    XCTAssertFalse([delegate application:_mockApplication
+                                 openURL:_url
+                       sourceApplication:@"sourceApplication"
+                              annotation:@"annotaton"]);
+  }
 }
 
 /** @fn testLegacyDelegateTwoHandlers
@@ -263,9 +360,17 @@ NS_ASSUME_NONNULL_BEGIN
         [[FIRAuthAppDelegateProxy alloc] initWithApplication:_mockApplication];
     XCTAssertNotNil(proxy);
 
-    // Verify `application:didReceiveRemoteNotification:fetchCompletionHandler` is not swizzled.
+    // Verify certain methods are swizzled while others are not.
+    XCTAssertTrue([delegate respondsToSelector:
+                   @selector(application:didRegisterForRemoteNotificationsWithDeviceToken:)]);
     XCTAssertFalse([delegate respondsToSelector:
                     @selector(application:didReceiveRemoteNotification:fetchCompletionHandler:)]);
+    XCTAssertTrue([delegate respondsToSelector:
+                   @selector(application:didReceiveRemoteNotification:)]);
+    XCTAssertFalse([delegate respondsToSelector:@selector(application:openURL:options:)]);
+    XCTAssertTrue([delegate respondsToSelector:
+                   @selector(application:openURL:sourceApplication:annotation:)]);
+    XCTAssertFalse([delegate respondsToSelector:@selector(application:handleOpenURL:)]);
 
     // Verify the handler is called after being added.
     __weak id weakHandler1;
@@ -277,7 +382,7 @@ NS_ASSUME_NONNULL_BEGIN
         id mockHandler2 = OCMProtocolMock(@protocol(FIRAuthAppDelegateHandler));
         [proxy addHandler:mockHandler2];
 
-        // Verify handling of `application:didRegisterForRemoteNotificationsWithDeviceToken:`.
+        // Verify `application:didRegisterForRemoteNotificationsWithDeviceToken:` is handled.
         OCMExpect([mockHandler1 setAPNSToken:_deviceToken]);
         OCMExpect([mockHandler2 setAPNSToken:_deviceToken]);
         [delegate application:_mockApplication
@@ -285,7 +390,7 @@ NS_ASSUME_NONNULL_BEGIN
         OCMVerifyAll(mockHandler1);
         OCMVerifyAll(mockHandler2);
 
-        // Verify handling of `application:didReceiveRemoteNotification:fetchCompletionHandler:`.
+        // Verify `application:didReceiveRemoteNotification:fetchCompletionHandler:` is handled.
         OCMExpect([mockHandler1 canHandleNotification:_notification]).andReturn(YES);
         // handler2 shouldn't been invoked because it is already handled by handler1.
         [delegate application:_mockApplication didReceiveRemoteNotification:_notification];
@@ -293,25 +398,45 @@ NS_ASSUME_NONNULL_BEGIN
         OCMVerifyAll(mockHandler2);
         XCTAssertNil(delegate.notificationReceived);
 
+        // Verify `application:openURL:sourceApplication:annotation:` is handled.
+        OCMExpect([mockHandler1 canHandleURL:_url]).andReturn(YES);
+        XCTAssertTrue([delegate application:_mockApplication
+                                    openURL:_url
+                          sourceApplication:@"sourceApplication"
+                                 annotation:@"annotaton"]);
+        OCMVerifyAll(mockHandler1);
+        OCMVerifyAll(mockHandler2);
+        XCTAssertNil(delegate.urlOpened);
+
         weakHandler2 = mockHandler2;
         XCTAssertNotNil(weakHandler2);
       }
       // Verify the handler2 is not retained by the proxy.
       XCTAssertNil(weakHandler2);
 
-      // Verify handling of `application:didRegisterForRemoteNotificationsWithDeviceToken:`.
+      // Verify `application:didRegisterForRemoteNotificationsWithDeviceToken:` is handled.
       OCMExpect([mockHandler1 setAPNSToken:_deviceToken]);
       [delegate application:_mockApplication
           didRegisterForRemoteNotificationsWithDeviceToken:_deviceToken];
       OCMVerifyAll(mockHandler1);
 
-      // Verify NOT handling of `application:didReceiveRemoteNotification:fetchCompletionHandler:`.
+      // Verify `application:didReceiveRemoteNotification:fetchCompletionHandler:` is NOT handled.
       OCMExpect([mockHandler1 canHandleNotification:_notification]).andReturn(NO);
       [delegate application:_mockApplication didReceiveRemoteNotification:_notification];
       OCMVerifyAll(mockHandler1);
       XCTAssertEqualObjects(delegate.notificationReceived, _notification);
       delegate.notificationReceived = nil;
 
+      // Verify `application:openURL:sourceApplication:annotation:` is NOT handled.
+      OCMExpect([mockHandler1 canHandleURL:_url]).andReturn(NO);
+      XCTAssertFalse([delegate application:_mockApplication
+                                   openURL:_url
+                         sourceApplication:@"sourceApplication"
+                                annotation:@"annotation"]);
+      OCMVerifyAll(mockHandler1);
+      XCTAssertEqualObjects(delegate.urlOpened, _url);
+      delegate.urlOpened = nil;
+
       weakHandler1 = mockHandler1;
       XCTAssertNotNil(weakHandler1);
     }
@@ -324,6 +449,12 @@ NS_ASSUME_NONNULL_BEGIN
     [delegate application:_mockApplication didReceiveRemoteNotification:_notification];
     XCTAssertEqualObjects(delegate.notificationReceived, _notification);
     delegate.notificationReceived = nil;
+    XCTAssertFalse([delegate application:_mockApplication
+                                 openURL:_url
+                       sourceApplication:@"sourceApplication"
+                              annotation:@"annotation"]);
+    XCTAssertEqualObjects(delegate.urlOpened, _url);
+    delegate.urlOpened = nil;
 
     weakProxy = proxy;
     XCTAssertNotNil(weakProxy);
@@ -337,6 +468,12 @@ NS_ASSUME_NONNULL_BEGIN
   [delegate application:_mockApplication didReceiveRemoteNotification:_notification];
   XCTAssertEqualObjects(delegate.notificationReceived, _notification);
   delegate.notificationReceived = nil;
+  XCTAssertFalse([delegate application:_mockApplication
+                               openURL:_url
+                     sourceApplication:@"sourceApplication"
+                            annotation:@"annotation"]);
+  XCTAssertEqualObjects(delegate.urlOpened, _url);
+  delegate.urlOpened = nil;
 }
 
 /** @fn testModernDelegateWithOtherInstance
@@ -353,9 +490,22 @@ NS_ASSUME_NONNULL_BEGIN
         [[FIRAuthAppDelegateProxy alloc] initWithApplication:_mockApplication];
     XCTAssertNotNil(proxy);
 
-    // Verify `application:didReceiveRemoteNotification:` is not swizzled.
+    // Verify certain methods are swizzled while others are not.
+    XCTAssertTrue([delegate respondsToSelector:
+                   @selector(application:didRegisterForRemoteNotificationsWithDeviceToken:)]);
+    XCTAssertTrue([delegate respondsToSelector:
+                   @selector(application:didReceiveRemoteNotification:fetchCompletionHandler:)]);
     XCTAssertFalse([delegate respondsToSelector:
                     @selector(application:didReceiveRemoteNotification:)]);
+    XCTAssertTrue([delegate respondsToSelector:@selector(application:openURL:options:)]);
+    if (&UIApplicationOpenURLOptionsAnnotationKey) {  // iOS 9+
+      XCTAssertFalse([delegate respondsToSelector:
+                      @selector(application:openURL:sourceApplication:annotation:)]);
+    } else {
+      XCTAssertTrue([delegate respondsToSelector:
+                     @selector(application:openURL:sourceApplication:annotation:)]);
+    }
+    XCTAssertFalse([delegate respondsToSelector:@selector(application:handleOpenURL:)]);
 
     // Verify the handler is called after being added.
     __weak id weakHandler;
@@ -363,7 +513,7 @@ NS_ASSUME_NONNULL_BEGIN
       id mockHandler = OCMProtocolMock(@protocol(FIRAuthAppDelegateHandler));
       [proxy addHandler:mockHandler];
 
-      // Verify handling of `application:didRegisterForRemoteNotificationsWithDeviceToken:`.
+      // Verify `application:didRegisterForRemoteNotificationsWithDeviceToken:` is handled.
       OCMExpect([mockHandler setAPNSToken:_deviceToken]);
       [delegate application:_mockApplication
           didRegisterForRemoteNotificationsWithDeviceToken:_deviceToken];
@@ -371,7 +521,7 @@ NS_ASSUME_NONNULL_BEGIN
       XCTAssertEqualObjects(delegate.deviceTokenReceived, _deviceToken);
       delegate.deviceTokenReceived = nil;
 
-      // Verify handling of `application:didReceiveRemoteNotification:fetchCompletionHandler:`.
+      // Verify `application:didReceiveRemoteNotification:fetchCompletionHandler:` is handled.
       OCMExpect([mockHandler canHandleNotification:_notification]).andReturn(YES);
       __block BOOL fetchCompletionHandlerCalled = NO;
       [delegate application:_mockApplication
@@ -384,6 +534,21 @@ NS_ASSUME_NONNULL_BEGIN
       XCTAssertTrue(fetchCompletionHandlerCalled);
       XCTAssertNil(delegate.notificationReceived);
 
+      // Verify one of the `application:openURL:...` methods is handled.
+      OCMExpect([mockHandler canHandleURL:_url]).andReturn(YES);
+      if (&UIApplicationOpenURLOptionsAnnotationKey) {  // iOS 9+
+        // Verify `application:openURL:options:` is handled.
+        XCTAssertTrue([delegate application:_mockApplication openURL:_url options:@{}]);
+      } else {
+        // Verify `application:openURL:sourceApplication:annotation:` is handled.
+        XCTAssertTrue([delegate application:_mockApplication
+                                    openURL:_url
+                          sourceApplication:@"sourceApplication"
+                                 annotation:@"annotaton"]);
+      }
+      OCMVerifyAll(mockHandler);
+      XCTAssertNil(delegate.urlOpened);
+
       // Verify unaffected delegate instance.
       [unaffectedDelegate application:_mockApplication
           didRegisterForRemoteNotificationsWithDeviceToken:_deviceToken];
@@ -399,6 +564,9 @@ NS_ASSUME_NONNULL_BEGIN
       XCTAssertTrue(fetchCompletionHandlerCalled);
       XCTAssertEqualObjects(unaffectedDelegate.notificationReceived, _notification);
       unaffectedDelegate.notificationReceived = nil;
+      XCTAssertFalse([unaffectedDelegate application:_mockApplication openURL:_url options:@{}]);
+      XCTAssertEqualObjects(unaffectedDelegate.urlOpened, _url);
+      unaffectedDelegate.urlOpened = nil;
 
       weakHandler = mockHandler;
       XCTAssertNotNil(weakHandler);
@@ -421,6 +589,9 @@ NS_ASSUME_NONNULL_BEGIN
     XCTAssertEqualObjects(delegate.notificationReceived, _notification);
     delegate.notificationReceived = nil;
     XCTAssertTrue(fetchCompletionHandlerCalled);
+    XCTAssertFalse([delegate application:_mockApplication openURL:_url options:@{}]);
+    XCTAssertEqualObjects(delegate.urlOpened, _url);
+    delegate.urlOpened = nil;
 
     weakProxy = proxy;
     XCTAssertNotNil(weakProxy);
@@ -443,6 +614,61 @@ NS_ASSUME_NONNULL_BEGIN
   XCTAssertEqualObjects(delegate.notificationReceived, _notification);
   delegate.notificationReceived = nil;
   XCTAssertTrue(fetchCompletionHandlerCalled);
+  XCTAssertFalse([delegate application:_mockApplication openURL:_url options:@{}]);
+  XCTAssertEqualObjects(delegate.urlOpened, _url);
+  delegate.urlOpened = nil;
+}
+
+/** @fn testOtherLegacyDelegateHandleOpenURL
+    @brief Tests that the proxy works against another legacy @c UIApplicationDelegate for
+        `application:handleOpenURL:`.
+ */
+- (void)testOtherLegacyDelegateHandleOpenURL {
+  FIRAuthOtherLegacyAppDelegate *delegate = [[FIRAuthOtherLegacyAppDelegate alloc] init];
+  OCMExpect([_mockApplication delegate]).andReturn(delegate);
+  __weak id weakProxy;
+  @autoreleasepool {
+    FIRAuthAppDelegateProxy *proxy =
+        [[FIRAuthAppDelegateProxy alloc] initWithApplication:_mockApplication];
+    XCTAssertNotNil(proxy);
+
+    // Verify certain methods are swizzled while others are not.
+    XCTAssertFalse([delegate respondsToSelector:@selector(application:openURL:options:)]);
+    XCTAssertFalse([delegate respondsToSelector:
+                    @selector(application:openURL:sourceApplication:annotation:)]);
+    XCTAssertTrue([delegate respondsToSelector:@selector(application:handleOpenURL:)]);
+
+    // Verify the handler is called after being added.
+    __weak id weakHandler;
+    @autoreleasepool {
+      id mockHandler = OCMProtocolMock(@protocol(FIRAuthAppDelegateHandler));
+      [proxy addHandler:mockHandler];
+
+      // Verify `application:handleOpenURL:` is handled.
+      OCMExpect([mockHandler canHandleURL:_url]).andReturn(YES);
+      XCTAssertTrue([delegate application:_mockApplication handleOpenURL:_url]);
+      OCMVerifyAll(mockHandler);
+
+      weakHandler = mockHandler;
+      XCTAssertNotNil(weakHandler);
+    }
+    // Verify the handler is not retained by the proxy.
+    XCTAssertNil(weakHandler);
+
+    // Verify nothing bad happens after the handler is released.
+    XCTAssertFalse([delegate application:_mockApplication handleOpenURL:_url]);
+    XCTAssertEqualObjects(delegate.urlOpened, _url);
+    delegate.urlOpened = nil;
+
+    weakProxy = proxy;
+    XCTAssertNotNil(weakProxy);
+  }
+  // Verify the proxy does not retain itself.
+  XCTAssertNil(weakProxy);
+  // Verify nothing bad happens after the proxy is released.
+  XCTAssertFalse([delegate application:_mockApplication handleOpenURL:_url]);
+  XCTAssertEqualObjects(delegate.urlOpened, _url);
+  delegate.urlOpened = nil;
 }
 
 @end
diff --git a/Firebase/Auth/Source/FIRAuth.m b/Firebase/Auth/Source/FIRAuth.m
index 33af19e..0a8af0e 100644
--- a/Firebase/Auth/Source/FIRAuth.m
+++ b/Firebase/Auth/Source/FIRAuth.m
@@ -980,6 +980,10 @@ static NSMutableDictionary *gKeychainServiceNameForAppName;
 }
 #endif
 
+- (BOOL)canHandleURL:(NSURL *)url {
+  return NO;
+}
+
 #pragma mark - Internal Methods
 
 #if TARGET_OS_IOS
diff --git a/Firebase/Auth/Source/FIRAuthAppDelegateProxy.h b/Firebase/Auth/Source/FIRAuthAppDelegateProxy.h
index 656e4f2..d974e2c 100644
--- a/Firebase/Auth/Source/FIRAuthAppDelegateProxy.h
+++ b/Firebase/Auth/Source/FIRAuthAppDelegateProxy.h
@@ -37,6 +37,13 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (BOOL)canHandleNotification:(nonnull NSDictionary *)notification;
 
+/** @fn canHandleURL:
+    @brief Checks whether the URL can be handled by the receiver, and handles it if so.
+    @param url The URL in question, which will be consumed if returns @c YES.
+    @return Whether the URL can be (and already has been) handled by the receiver.
+ */
+- (BOOL)canHandleURL:(nonnull NSURL *)url;
+
 @end
 
 /** @class FIRAuthAppDelegateProxy
diff --git a/Firebase/Auth/Source/FIRAuthAppDelegateProxy.m b/Firebase/Auth/Source/FIRAuthAppDelegateProxy.m
index f24765a..15151f3 100644
--- a/Firebase/Auth/Source/FIRAuthAppDelegateProxy.m
+++ b/Firebase/Auth/Source/FIRAuthAppDelegateProxy.m
@@ -107,6 +107,53 @@ static id noop(id object, SEL cmd, ...) {
             didReceiveRemoteNotification:notification];
       }];
     }
+    SEL openURLOptionsSelector = @selector(application:openURL:options:);
+    SEL openURLAnnotationSelector = @selector(application:openURL:sourceApplication:annotation:);
+    SEL handleOpenURLSelector = @selector(application:handleOpenURL:);
+    if (&UIApplicationOpenURLOptionsAnnotationKey &&  // the constant is only available on iOS 9+
+        ([_appDelegate respondsToSelector:openURLOptionsSelector] ||
+         (![_appDelegate respondsToSelector:openURLAnnotationSelector] &&
+          ![_appDelegate respondsToSelector:handleOpenURLSelector]))) {
+      // Replace the modern selector which is avaliable on iOS 9 and above because this is the one
+      // that the client app uses or the client app doesn't use any of them.
+      [self replaceSelector:openURLOptionsSelector
+                  withBlock:^BOOL(id object, UIApplication *application, NSURL *url,
+                                  NSDictionary *options) {
+        return [weakSelf object:object
+                       selector:openURLOptionsSelector
+                    application:application
+                        openURL:url
+                        options:options];
+       }];
+    } else if ([_appDelegate respondsToSelector:openURLAnnotationSelector] ||
+               ![_appDelegate respondsToSelector:handleOpenURLSelector]) {
+      // Replace the longer form of the deprecated selectors on iOS 8 and below because this is the
+      // one that the client app uses or the client app doesn't use either of the applicable ones.
+      [self replaceSelector:openURLAnnotationSelector
+                  withBlock:^(id object, UIApplication *application, NSURL *url,
+                              NSString *sourceApplication, id annotation) {
+        return [weakSelf object:object
+                       selector:openURLAnnotationSelector
+                    application:application
+                        openURL:url
+              sourceApplication:sourceApplication
+                     annotation:annotation];
+       }];
+    } else {
+      // Replace the shorter form of the deprecated selectors on iOS 8 and below because this is
+      // the only one that the client app uses.
+      [self replaceSelector:handleOpenURLSelector
+                  withBlock:^(id object, UIApplication *application, NSURL *url) {
+        return [weakSelf object:object
+                       selector:handleOpenURLSelector
+                    application:application
+                  handleOpenURL:url];
+       }];
+    }
+    // Reset the application delegate to clear the system cache that indicates whether each of the
+    // openURL: methods is implemented on the application delegate.
+    application.delegate = nil;
+    application.delegate = _appDelegate;
   }
   return self;
 }
@@ -146,7 +193,7 @@ static id noop(id object, SEL cmd, ...) {
     }
   }
   IMP originalImplementation = [self originalImplementationForSelector:selector];
-  if (originalImplementation) {
+  if (originalImplementation && originalImplementation != &noop) {
     typedef void (*Implmentation)(id, SEL, UIApplication*, NSData *);
     ((Implmentation)originalImplementation)(object, selector, application, deviceToken);
   }
@@ -166,10 +213,12 @@ static id noop(id object, SEL cmd, ...) {
     }
   }
   IMP originalImplementation = [self originalImplementationForSelector:selector];
-  typedef void (*Implmentation)(id, SEL, UIApplication*, NSDictionary *,
-                                void (^)(UIBackgroundFetchResult));
-  ((Implmentation)originalImplementation)(object, selector, application, notification,
-                                          completionHandler);
+  if (originalImplementation && originalImplementation != &noop) {
+    typedef void (*Implmentation)(id, SEL, UIApplication*, NSDictionary *,
+                                  void (^)(UIBackgroundFetchResult));
+    ((Implmentation)originalImplementation)(object, selector, application, notification,
+                                            completionHandler);
+  }
 }
 
 - (void)object:(id)object
@@ -184,12 +233,77 @@ static id noop(id object, SEL cmd, ...) {
     }
   }
   IMP originalImplementation = [self originalImplementationForSelector:selector];
-  typedef void (*Implmentation)(id, SEL, UIApplication*, NSDictionary *);
-  ((Implmentation)originalImplementation)(object, selector, application, notification);
+  if (originalImplementation && originalImplementation != &noop) {
+    typedef void (*Implmentation)(id, SEL, UIApplication*, NSDictionary *);
+    ((Implmentation)originalImplementation)(object, selector, application, notification);
+  }
+}
+
+- (BOOL)object:(id)object
+       selector:(SEL)selector
+    application:(UIApplication *)application
+        openURL:(NSURL *)url
+        options:(NSDictionary *)options {
+  if (object == _appDelegate && [self delegateCanHandleURL:url]) {
+    return YES;
+  }
+  IMP originalImplementation = [self originalImplementationForSelector:selector];
+  if (originalImplementation && originalImplementation != &noop) {
+    typedef BOOL (*Implmentation)(id, SEL, UIApplication*, NSURL *, NSDictionary *);
+    return ((Implmentation)originalImplementation)(object, selector, application, url, options);
+  }
+  return NO;
+}
+
+- (BOOL)object:(id)object
+             selector:(SEL)selector
+          application:(UIApplication *)application
+              openURL:(NSURL *)url
+    sourceApplication:(NSString *)sourceApplication
+           annotation:(id)annotation {
+  if (object == _appDelegate && [self delegateCanHandleURL:url]) {
+    return YES;
+  }
+  IMP originalImplementation = [self originalImplementationForSelector:selector];
+  if (originalImplementation && originalImplementation != &noop) {
+    typedef BOOL (*Implmentation)(id, SEL, UIApplication*, NSURL *, NSString *, id);
+    return ((Implmentation)originalImplementation)(object, selector, application, url,
+                                                   sourceApplication, annotation);
+  }
+  return NO;
+}
+
+- (BOOL)object:(id)object
+         selector:(SEL)selector
+      application:(UIApplication *)application
+    handleOpenURL:(NSURL *)url {
+  if (object == _appDelegate && [self delegateCanHandleURL:url]) {
+    return YES;
+  }
+  IMP originalImplementation = [self originalImplementationForSelector:selector];
+  if (originalImplementation && originalImplementation != &noop) {
+    typedef BOOL (*Implmentation)(id, SEL, UIApplication*, NSURL *);
+    return ((Implmentation)originalImplementation)(object, selector, application, url);
+  }
+  return NO;
 }
 
 #pragma mark - Internal Methods
 
+/** @fn delegateCanHandleURL:
+    @brief Checks for whether any of the delegates can handle the URL.
+    @param url The URL in question.
+    @return Whether any of the delegate can handle the URL.
+ */
+- (BOOL)delegateCanHandleURL:(NSURL *)url {
+  for (id<FIRAuthAppDelegateHandler> handler in [self handlers]) {
+    if ([handler canHandleURL:url]) {
+      return YES;
+    };
+  }
+  return NO;
+}
+
 /** @fn handlers
     @brief Gets the list of handlers from `_handlers` safely.
  */
diff --git a/Firebase/Auth/Source/Public/FIRAuth.h b/Firebase/Auth/Source/Public/FIRAuth.h
index ad6b635..f2b00ae 100644
--- a/Firebase/Auth/Source/Public/FIRAuth.h
+++ b/Firebase/Auth/Source/Public/FIRAuth.h
@@ -684,6 +684,18 @@ FIR_SWIFT_NAME(Auth)
 - (BOOL)canHandleNotification:(NSDictionary *)userInfo;
 #endif
 
+/** @fn canHandleURL:
+    @brief Whether the specific URL is handled by @c FIRAuth .
+    @param url The URL received by the application delegate from any of the openURL method.
+    @return Whether or the URL is handled. YES means the URL is for Firebase Auth
+        so the caller should ignore the URL from further processing, and NO means the
+        the URL is for the app (or another libaray) so the caller should continue handling
+        this URL as usual.
+    @remarks If swizzling is disabled, URLs received by the application delegate must be forwarded
+        to this method for phone number auth to work.
+ */
+- (BOOL)canHandleURL:(nonnull NSURL *)url;
+
 @end
 
 NS_ASSUME_NONNULL_END