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    Get Started with Firebase Authentication on Apple Platforms

    You can use Firebase Authentication to allow users to sign in to your app using one or more sign-in methods, including email address and password sign-in, and federated identity providers such as Google Sign-in and Facebook Login. This tutorial gets you started with Firebase Authentication by showing you how to add email address and password sign-in to your app.

    Connect your app to Firebase

    1. Install the Firebase SDK .
    2. In the Firebase console , add your app to your Firebase project.

    Add Firebase Authentication to your app

    Use Swift Package Manager to install and manage Firebase dependencies.

    1. In Xcode, with your app project open, navigate to File > Add Packages .
    2. When prompted, add the Firebase Apple platforms SDK repository:
      3. https://github.com/firebase/firebase-ios-sdk.git
    3. Choose the Firebase Authentication library.
    4. Add the -ObjC flag to the Other Linker Flags section of your target's build settings.
    5. When finished, Xcode will automatically begin resolving and downloading your dependencies in the background.

    (Optional) Prototype and test with Firebase Local Emulator Suite

    Before talking about how your app authenticates users, let's introduce a set of tools you can use to prototype and test Authentication functionality: Firebase Local Emulator Suite . If you're deciding among authentication techniques and providers, trying out different data models with public and private data using Authentication and Firebase Security Rules , or prototyping sign-in UI designs, being able to work locally without deploying live services can be a great idea.

    An Authentication emulator is part of the Local Emulator Suite , which enables your app to interact with emulated database content and config, as well as optionally your emulated project resources (functions, other databases, and security rules).

    Using the Authentication emulator involves just a few steps:

    1. Adding a line of code to your app's test config to connect to the emulator.
    2. From the root of your local project directory, running firebase emulators:start .
    3. Using the Local Emulator Suite UI for interactive prototyping, or the Authentication emulator REST API for non-interactive testing.

    A detailed guide is available at Connect your app to the Authentication emulator . For more information, see the Local Emulator Suite introduction .

    Now let's continue with how to authenticate users.

    Initialize the Firebase SDK

    In your app delegate, first import the Firebase SDK:

    Swift

      import 
  
 FirebaseCore 
     AppDelegate 

     
     
 . 
 swift

    Objective-C

      @import 
  
 FirebaseCore 
 ; 
 
      AppDelegate 
 . 
 m

    Then, in the application:didFinishLaunchingWithOptions: method, initialize the FirebaseApp object:

    Swift

      // Use Firebase library to configure APIs 
 FirebaseApp 
 . 
 configure 
 () 
 
      AppDelegate 
 . 
 swift

    Objective-C

      // Use Firebase library to configure APIs 
 [ 
 FIRApp 
  
 configure 
 ]; 
 
      AppDelegate 
 . 
 m

    Listen for authentication state

    For each of your app's views that need information about the signed-in user, attach a listener to the FIRAuth object. This listener gets called whenever the user's sign-in state changes.

    Attach the listener in the view controller's viewWillAppear method:

    Swift

      handle 
  
 = 
  
 Auth 
 . 
 auth 
 (). 
 addStateDidChangeListener 
  
 { 
  
 auth 
 , 
  
 user 
  
 in 
  
 // ... 
 } 
 
      MainViewController 
 . 
 swift

    Objective-C

      self 
 . 
 handle 
  
 = 
  
 [[ 
 FIRAuth 
  
 auth 
 ] 
  
 addAuthStateDidChangeListener 
 : 
 ^ 
 ( 
 FIRAuth 
  
 * 
 _Nonnull 
  
 auth 
 , 
  
 FIRUser 
  
 * 
 _Nullable 
  
 user 
 ) 
  
 { 
  
 // ... 
  
 }]; 
 
      MainViewController 
 . 
 m

    And detach the listener in the view controller's viewWillDisappear method:

    Swift

      Auth 
 . 
 auth 
 (). 
 removeStateDidChangeListener 
 ( 
 handle 
 !) 
 
      MainViewController 
 . 
 swift

    Objective-C

      [[ 
 FIRAuth 
  
 auth 
 ] 
  
 removeAuthStateDidChangeListener 
 : 
 _handle 
 ]; 
 
      MainViewController 
 . 
 m

    Create a form that allows new users to register with your app using their email address and a password. When a user completes the form, validate the email address and password provided by the user, then pass them to the createUser method:

    Swift

      Auth 
 . 
 auth 
 (). 
 createUser 
 ( 
 withEmail 
 : 
  
 email 
 , 
  
 password 
 : 
  
 password 
 ) 
  
 { 
  
 authResult 
 , 
  
 error 
  
 in 
  
 // ... 
 } 
 
      EmailViewController 
 . 
 swift

    Objective-C

      [[ 
 FIRAuth 
  
 auth 
 ] 
  
 createUserWithEmail 
 : 
 email 
  
 password 
 : 
 password 
  
 completion 
 : 
 ^ 
 ( 
 FIRAuthDataResult 
  
 * 
  
 _Nullable 
  
 authResult 
 , 
  
 NSError 
  
 * 
  
 _Nullable 
  
 error 
 ) 
  
 { 
  
 // ... 
 }]; 
 
      EmailViewController 
 . 
 m

    Create a form that allows existing users to sign in using their email address and password. When a user completes the form, call the signIn method:

    Swift

      Auth 
 . 
 auth 
 (). 
 signIn 
 ( 
 withEmail 
 : 
  
 email 
 , 
  
 password 
 : 
  
 password 
 ) 
  
 { 
  
 [ 
 weak 
  
 self 
 ] 
  
 authResult 
 , 
  
 error 
  
 in 
  
 guard 
  
 let 
  
 strongSelf 
  
 = 
  
 self 
  
 else 
  
 { 
  
 return 
  
 } 
  
 // ... 
 } 
 
      EmailViewController 
 . 
 swift

    Objective-C

      [[ 
 FIRAuth 
  
 auth 
 ] 
  
 signInWithEmail 
 : 
 self 
 - 
> _emailField 
 . 
 text 
  
 password 
 : 
 self 
 - 
> _passwordField 
 . 
 text 
  
 completion 
 : 
 ^ 
 ( 
 FIRAuthDataResult 
  
 * 
  
 _Nullable 
  
 authResult 
 , 
  
 NSError 
  
 * 
  
 _Nullable 
  
 error 
 ) 
  
 { 
  
 // ... 
 }]; 
 
      EmailViewController 
 . 
 m

    Get user information

    After a user signs in successfully, you can get information about the user. For example, in your authentication state listener :

    Swift

      if 
  
 let 
  
 user 
  
 = 
  
 user 
  
 { 
  
 // The user's ID, unique to the Firebase project. 
  
 // Do NOT use this value to authenticate with your backend server, 
  
 // if you have one. Use getTokenWithCompletion:completion: instead. 
  
 let 
  
 uid 
  
 = 
  
 user 
 . 
 uid 
  
 let 
  
 email 
  
 = 
  
 user 
 . 
 email 
  
 let 
  
 photoURL 
  
 = 
  
 user 
 . 
 photoURL 
  
 var 
  
 multiFactorString 
  
 = 
  
 "MultiFactor: " 
  
 for 
  
 info 
  
 in 
  
 user 
 . 
 multiFactor 
 . 
 enrolledFactors 
  
 { 
  
 multiFactorString 
  
 += 
  
 info 
 . 
 displayName 
  
 ?? 
  
 "[DispayName]" 
  
 multiFactorString 
  
 += 
  
 " " 
  
 } 
  
 // ... 
 } 
 
      MainViewController 
 . 
 swift

    Objective-C

      if 
  
 ( 
 user 
 ) 
  
 { 
  
 // The user's ID, unique to the Firebase project. 
  
 // Do NOT use this value to authenticate with your backend server, 
  
 // if you have one. Use getTokenWithCompletion:completion: instead. 
  
 NSString 
  
 * 
 email 
  
 = 
  
 user 
 . 
 email 
 ; 
  
 NSString 
  
 * 
 uid 
  
 = 
  
 user 
 . 
 uid 
 ; 
  
 NSMutableString 
  
 * 
 multiFactorString 
  
 = 
  
 [ 
 NSMutableString 
  
 stringWithFormat 
 : 
 @"MultiFactor: " 
 ]; 
  
 for 
  
 ( 
 FIRMultiFactorInfo 
  
 * 
 info 
  
 in 
  
 user 
 . 
 multiFactor 
 . 
 enrolledFactors 
 ) 
  
 { 
  
 [ 
 multiFactorString 
  
 appendString 
 : 
 info 
 . 
 displayName 
 ]; 
  
 [ 
 multiFactorString 
  
 appendString 
 : 
 @" " 
 ]; 
  
 } 
  
 NSURL 
  
 * 
 photoURL 
  
 = 
  
 user 
 . 
 photoURL 
 ; 
  
 // ... 
 } 
 
      MainViewController 
 . 
 m

    Next steps

    Learn how to add support for other identity providers and anonymous guest accounts:

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