Authenticate Using Google Sign-In on Apple Platforms

You can let your users authenticate with Firebase using their Google Accounts by integrating Google Sign-In into your app.

Before you begin

Use Swift Package Manager to install and manage Firebase dependencies.

In Xcode, with your app project open, navigate to File > Add Packages .
When prompted, add the Firebase Apple platforms SDK repository:

https://github.com/firebase/firebase-ios-sdk.git

Choose the Firebase Authentication library.
Add the -ObjC flag to the Other Linker Flags section of your target's build settings.
When finished, Xcode will automatically begin resolving and downloading your dependencies in the background.

Add the Google Sign-In SDK to your project

In Xcode, with your app project open, navigate to File > Add Packages.
When prompted, add the Google Sign-In SDK repository:
```
 https://github.com/google/GoogleSignIn-iOS 
```
When finished, Xcode will automatically begin resolving and downloading your dependencies in the background.

Enable Google Sign-In for your Firebase project

To allow users to sign in using Google Sign-In, you must first enable the Google Sign-In provider for your Firebase project:

In the Firebase console , open the Authenticationsection.
On the Sign in methodtab, enable the Googleprovider.
Click Save.
Download a new copy of your project's GoogleService-Info.plist file and copy it to your Xcode project. Overwrite any existing versions with the new one. (See Add Firebase to your iOS project .)

Import the required header files

First, you must import the Firebase SDK and Google Sign-In SDK header files into your app.

Swift

 import 
  
 FirebaseCore 
 import 
  
 FirebaseAuth 
 import 
  
 GoogleSignIn

Objective-C

 @import 
  
 FirebaseCore 
 ; 
 @import 
  
 GoogleSignIn 
 ;

Implement Google Sign-In

Implement Google Sign-In by following these steps. See the Google Sign-In developer documentation for details on using Google Sign-In with iOS.

Add custom URL schemes to your Xcode project:

Open your project configuration: click the project name in the left tree view. Select your app from the TARGETS section, then select the Info tab, and expand the URL Types section.
Click the + button, and add a URL scheme for your reversed client ID. To find this value, open the GoogleService-Info.plist configuration file, and look for the REVERSED_CLIENT_ID key. Copy the value of that key, and paste it into the URL Schemes box on the configuration page. Leave the other fields untouched.
When completed, your config should look something similar to the following (but with your application-specific values):

In your app delegate's application:didFinishLaunchingWithOptions: method, configure the FirebaseApp object.

Swift

 FirebaseApp 
 . 
 configure 
 ()

Objective-C

 // Use Firebase library to configure APIs 
 [ 
 FIRApp 
  
 configure 
 ];

Implement the application:openURL:options: method of your app delegate. The method should call the handleURL method of the GIDSignIn instance, which will properly handle the URL that your application receives at the end of the authentication process.

Swift

 func 
  
 application 
 ( 
 _ 
  
 app 
 : 
  
 UIApplication 
 , 
  
 open 
  
 url 
 : 
  
 URL 
 , 
  
 options 
 : 
  
 [ 
 UIApplication 
 . 
 OpenURLOptionsKey 
 : 
  
 Any 
 ] 
  
 = 
  
 [:]) 
  
 - 
>  
 Bool 
  
 { 
  
 return 
  
 GIDSignIn 
 . 
 sharedInstance 
 . 
 handle 
 ( 
 url 
 ) 
 }

Objective-C

 - 
 ( 
 BOOL 
 ) 
 application: 
 ( 
 nonnull 
  
 UIApplication 
  
 * 
 ) 
 application 
  
 openURL 
 :( 
 nonnull 
  
 NSURL 
  
 * 
 ) 
 url 
  
 options 
 :( 
 nonnull 
  
 NSDictionary<NSString 
  
 * 
 , 
  
 id 
>  
 * 
 ) 
 options 
  
 { 
  
 return 
  
 [[ 
 GIDSignIn 
  
 sharedInstance 
 ] 
  
 handleURL 
 : 
 url 
 ]; 
 }

Pass the presenting view controller and client ID for your app to the signIn method of the Google Sign-In provider and create a Firebase Authentication credential from the resulting Google auth token:

Swift

 guard 
  
 let 
  
 clientID 
  
 = 
  
 FirebaseApp 
 . 
 app 
 ()?. 
 options 
 . 
 clientID 
  
 else 
  
 { 
  
 return 
  
 } 
 // Create Google Sign In configuration object. 
 let 
  
 config 
  
 = 
  
 GIDConfiguration 
 ( 
 clientID 
 : 
  
 clientID 
 ) 
 GIDSignIn 
 . 
 sharedInstance 
 . 
 configuration 
  
 = 
  
 config 
 // Start the sign in flow! 
 GIDSignIn 
 . 
 sharedInstance 
 . 
 signIn 
 ( 
 withPresenting 
 : 
  
 self 
 ) 
  
 { 
  
 [ 
 unowned 
  
 self 
 ] 
  
 result 
 , 
  
 error 
  
 in 
  
 guard 
  
 error 
  
 == 
  
 nil 
  
 else 
  
 { 
  
 // ... 
  
 } 
  
 guard 
  
 let 
  
 user 
  
 = 
  
 result 
 ?. 
 user 
 , 
  
 let 
  
 idToken 
  
 = 
  
 user 
 . 
 idToken 
 ?. 
 tokenString 
  
 else 
  
 { 
  
 // ... 
  
 } 
  
 let 
  
 credential 
  
 = 
  
 GoogleAuthProvider 
 . 
 credential 
 ( 
 withIDToken 
 : 
  
 idToken 
 , 
  
 accessToken 
 : 
  
 user 
 . 
 accessToken 
 . 
 tokenString 
 ) 
  
 // ... 
 }

Objective-C

 GIDConfiguration 
  
 * 
 config 
  
 = 
  
 [[ 
 GIDConfiguration 
  
 alloc 
 ] 
  
 initWithClientID 
 : 
 [ 
 FIRApp 
  
 defaultApp 
 ]. 
 options 
 . 
 clientID 
 ]; 
 [ 
 GIDSignIn 
 . 
 sharedInstance 
  
 setConfiguration 
 : 
 config 
 ]; 
 __weak 
  
 __auto_type 
  
 weakSelf 
  
 = 
  
 self 
 ; 
 [ 
 GIDSignIn 
 . 
 sharedInstance 
  
 signInWithPresentingViewController 
 : 
 self 
  
 completion 
 : 
 ^ 
 ( 
 GIDSignInResult 
  
 * 
  
 _Nullable 
  
 result 
 , 
  
 NSError 
  
 * 
  
 _Nullable 
  
 error 
 ) 
  
 { 
  
 __auto_type 
  
 strongSelf 
  
 = 
  
 weakSelf 
 ; 
  
 if 
  
 ( 
 strongSelf 
  
 == 
  
 nil 
 ) 
  
 { 
  
 return 
 ; 
  
 } 
  
 if 
  
 ( 
 error 
  
 == 
  
 nil 
 ) 
  
 { 
  
 FIRAuthCredential 
  
 * 
 credential 
  
 = 
  
 [ 
 FIRGoogleAuthProvider 
  
 credentialWithIDToken 
 : 
 result 
 . 
 user 
 . 
 idToken 
 . 
 tokenString 
  
 accessToken 
 : 
 result 
 . 
 user 
 . 
 accessToken 
 . 
 tokenString 
 ]; 
  
 // ... 
  
 } 
  
 else 
  
 { 
  
 // ... 
  
 } 
 }];

Add a GIDSignInButton to your storyboard, XIB file, or instantiate it programmatically. To add the button to your storyboard or XIB file, add a View and set its custom class to GIDSignInButton .
When you add a GIDSignInButton view to your storyboard, the sign-in button doesn't render in the interface builder. Run the app to see the sign-in button.
Optional: If you want to customize the button, do the following:
Swift
1. In your view controller, declare the sign-in button as a property.
  @IBOutlet weak var signInButton : GIDSignInButton !
2. Connect the button to the signInButton property you just declared.
3. Customize the button by setting the properties of the GIDSignInButton object.
Objective-C
1. In your view controller's header file, declare the sign-in button as a property.
  @property ( weak , nonatomic ) IBOutlet GIDSignInButton * signInButton ;
2. Connect the button to the signInButton property you just declared.
3. Customize the button by setting the properties of the GIDSignInButton object.

Authenticate with Firebase

Finally, complete the Firebase login process with the auth credential created in the previous step.

Swift

 Auth 
 . 
 auth 
 (). 
 signIn 
 ( 
 with 
 : 
  
 credential 
 ) 
  
 { 
  
 result 
 , 
  
 error 
  
 in 
  
 // At this point, our user is signed in 
 }

Objective-C

 [[ 
 FIRAuth 
  
 auth 
 ] 
  
 signInWithCredential 
 : 
 credential 
  
 completion 
 : 
 ^ 
 ( 
 FIRAuthDataResult 
  
 * 
  
 _Nullable 
  
 authResult 
 , 
  
 NSError 
  
 * 
  
 _Nullable 
  
 error 
 ) 
  
 { 
  
 if 
  
 ( 
 isMFAEnabled 
 && 
 error 
 && 
 error 
 . 
 code 
  
 == 
  
 FIRAuthErrorCodeSecondFactorRequired 
 ) 
  
 { 
  
 FIRMultiFactorResolver 
  
 * 
 resolver 
  
 = 
  
 error 
 . 
 userInfo 
 [ 
 FIRAuthErrorUserInfoMultiFactorResolverKey 
 ]; 
  
 NSMutableString 
  
 * 
 displayNameString 
  
 = 
  
 [ 
 NSMutableString 
  
 string 
 ]; 
  
 for 
  
 ( 
 FIRMultiFactorInfo 
  
 * 
 tmpFactorInfo 
  
 in 
  
 resolver 
 . 
 hints 
 ) 
  
 { 
  
 [ 
 displayNameString 
  
 appendString 
 : 
 tmpFactorInfo 
 . 
 displayName 
 ]; 
  
 [ 
 displayNameString 
  
 appendString 
 : 
 @" " 
 ]; 
  
 } 
  
 [ 
 self 
  
 showTextInputPromptWithMessage 
 : 
 [ 
 NSString 
  
 stringWithFormat 
 : 
 @"Select factor to sign in 
 \n 
 %@" 
 , 
  
 displayNameString 
 ] 
  
 completionBlock 
 : 
 ^ 
 ( 
 BOOL 
  
 userPressedOK 
 , 
  
 NSString 
  
 * 
 _Nullable 
  
 displayName 
 ) 
  
 { 
  
 FIRPhoneMultiFactorInfo 
 * 
  
 selectedHint 
 ; 
  
 for 
  
 ( 
 FIRMultiFactorInfo 
  
 * 
 tmpFactorInfo 
  
 in 
  
 resolver 
 . 
 hints 
 ) 
  
 { 
  
 if 
  
 ([ 
 displayName 
  
 isEqualToString 
 : 
 tmpFactorInfo 
 . 
 displayName 
 ]) 
  
 { 
  
 selectedHint 
  
 = 
  
 ( 
 FIRPhoneMultiFactorInfo 
  
 * 
 ) 
 tmpFactorInfo 
 ; 
  
 } 
  
 } 
  
 [ 
 FIRPhoneAuthProvider 
 . 
 provider 
  
 verifyPhoneNumberWithMultiFactorInfo 
 : 
 selectedHint 
  
 UIDelegate 
 : 
 nil 
  
 multiFactorSession 
 : 
 resolver 
 . 
 session 
  
 completion 
 : 
 ^ 
 ( 
 NSString 
  
 * 
  
 _Nullable 
  
 verificationID 
 , 
  
 NSError 
  
 * 
  
 _Nullable 
  
 error 
 ) 
  
 { 
  
 if 
  
 ( 
 error 
 ) 
  
 { 
  
 [ 
 self 
  
 showMessagePrompt 
 : 
 error 
 . 
 localizedDescription 
 ]; 
  
 } 
  
 else 
  
 { 
  
 [ 
 self 
  
 showTextInputPromptWithMessage 
 : 
 [ 
 NSString 
  
 stringWithFormat 
 : 
 @"Verification code for %@" 
 , 
  
 selectedHint 
 . 
 displayName 
 ] 
  
 completionBlock 
 : 
 ^ 
 ( 
 BOOL 
  
 userPressedOK 
 , 
  
 NSString 
  
 * 
 _Nullable 
  
 verificationCode 
 ) 
  
 { 
  
 FIRPhoneAuthCredential 
  
 * 
 credential 
  
 = 
  
 [[ 
 FIRPhoneAuthProvider 
  
 provider 
 ] 
  
 credentialWithVerificationID 
 : 
 verificationID 
  
 verificationCode 
 : 
 verificationCode 
 ]; 
  
 FIRMultiFactorAssertion 
  
 * 
 assertion 
  
 = 
  
 [ 
 FIRPhoneMultiFactorGenerator 
  
 assertionWithCredential 
 : 
 credential 
 ]; 
  
 [ 
 resolver 
  
 resolveSignInWithAssertion 
 : 
 assertion 
  
 completion 
 :^ 
 ( 
 FIRAuthDataResult 
  
 * 
  
 _Nullable 
  
 authResult 
 , 
  
 NSError 
  
 * 
  
 _Nullable 
  
 error 
 ) 
  
 { 
  
 if 
  
 ( 
 error 
 ) 
  
 { 
  
 [ 
 self 
  
 showMessagePrompt 
 : 
 error 
 . 
 localizedDescription 
 ]; 
  
 } 
  
 else 
  
 { 
  
 NSLog 
 ( 
 @"Multi factor finanlize sign in succeeded." 
 ); 
  
 } 
  
 }]; 
  
 }]; 
  
 } 
  
 }]; 
  
 }]; 
  
 } 
  
 else 
  
 if 
  
 ( 
 error 
 ) 
  
 { 
  
 // ... 
  
 return 
 ; 
  
 } 
  
 // User successfully signed in. Get user data from the FIRUser object 
  
 if 
  
 ( 
 authResult 
  
 == 
  
 nil 
 ) 
  
 { 
  
 return 
 ; 
  
 } 
  
 FIRUser 
  
 * 
 user 
  
 = 
  
 authResult 
 . 
 user 
 ; 
  
 // ... 
 }];

Next steps

After a user signs in for the first time, a new user account is created and linked to the credentials—that is, the user name and password, phone number, or auth provider information—the user signed in with. This new account is stored as part of your Firebase project, and can be used to identify a user across every app in your project, regardless of how the user signs in.

In your apps, you can get the user's basic profile information from the User object. See Manage Users .
In your Firebase Realtime Database and Cloud Storage Security Rules , you can get the signed-in user's unique user ID from the auth variable, and use it to control what data a user can access.

You can allow users to sign in to your app using multiple authentication providers by linking auth provider credentials to an existing user account.

To sign out a user, call signOut: .

Swift

 let 
  
 firebaseAuth 
  
 = 
  
 Auth 
 . 
 auth 
 () 
 do 
  
 { 
  
 try 
  
 firebaseAuth 
 . 
 signOut 
 () 
 } 
  
 catch 
  
 let 
  
 signOutError 
  
 as 
  
 NSError 
  
 { 
  
 print 
 ( 
 "Error signing out: %@" 
 , 
  
 signOutError 
 ) 
 }

Objective-C

 NSError 
  
 * 
 signOutError 
 ; 
 BOOL 
  
 status 
  
 = 
  
 [[ 
 FIRAuth 
  
 auth 
 ] 
  
 signOut 
 : 
& signOutError 
 ]; 
 if 
  
 ( 
 ! 
 status 
 ) 
  
 { 
  
 NSLog 
 ( 
 @"Error signing out: %@" 
 , 
  
 signOutError 
 ); 
  
 return 
 ; 
 }

You may also want to add error handling code for the full range of authentication errors. See Handle Errors .

Authenticate Using Google Sign-In on Apple Platforms Stay organized with collections Save and categorize content based on your preferences.

Before you begin

Add the Google Sign-In SDK to your project

Enable Google Sign-In for your Firebase project

Import the required header files

Swift

Objective-C

Implement Google Sign-In

Swift

Objective-C

Swift

Objective-C

Swift

Objective-C

Swift

Objective-C

Authenticate with Firebase

Swift

Objective-C

Next steps

Swift

Objective-C

Authenticate Using Google Sign-In on Apple Platforms