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Authenticate with Firebase Anonymously on Apple Platforms

You can use Firebase Authentication to create and use temporary anonymous accounts to authenticate with Firebase. These temporary anonymous accounts can be used to allow users who haven't yet signed up to your app to work with data protected by security rules. If an anonymous user decides to sign up to your app, you can link their sign-in credentials to the anonymous account so that they can continue to work with their protected data in future sessions.

Before you begin

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:
  4. Choose the Firebase Authentication library.
  5. When finished, Xcode will automatically begin resolving and downloading your dependencies in the background.

Next, perform some configuration steps:

  1. If you haven't yet connected your app to your Firebase project, do so from the Firebase console.
  2. Enable anonymous auth:
    1. In the Firebase console, open the Auth section.
    2. On the Sign-in Methods page, enable the Anonymous sign-in method.
    3. Optional: Enable automatic clean-up. When you enable this setting, anonymous accounts older than 30 days will be automatically deleted. In projects with automatic clean-up enabled, anonymous authentication will no longer count toward usage limits or billing quotas. See Automatic clean-up.

Authenticate with Firebase anonymously

When a signed-out user uses an app feature that requires authentication with Firebase, sign in the user anonymously by completing the following steps:

  1. Import the FirebaseCore module in your UIApplicationDelegate, as well as any other Firebase modules your app delegate uses. For example, to use Cloud Firestore and Authentication:


    import FirebaseCore
    import FirebaseFirestore
    import FirebaseAuth
    // ...


    @import FirebaseCore;
    @import FirebaseFirestore;
    @import FirebaseAuth;
    // ...
  2. Configure a FirebaseApp shared instance in your app delegate's application(_:didFinishLaunchingWithOptions:) method:


    // Use Firebase library to configure APIs


    // Use Firebase library to configure APIs
    [FIRApp configure];
  3. Call the signInAnonymouslyWithCompletion: method:


    Auth.auth().signInAnonymously { authResult, error in
      // ...


    [[FIRAuth auth] signInAnonymouslyWithCompletion:^(FIRAuthDataResult * _Nullable authResult,
                                                      NSError * _Nullable error) {
       // ...
  4. If the signInAnonymouslyWithCompletion: method completes without error, you can get the anonymous user's account data from the FIRAuthDataResult object:


    guard let user = authResult?.user else { return }
    let isAnonymous = user.isAnonymous  // true
    let uid = user.uid


    FIRUser *user = authResult.user;
    BOOL isAnonymous = user.anonymous;  // YES
    NSString *uid = user.uid;

Convert an anonymous account to a permanent account

When an anonymous user signs up to your app, you might want to allow them to continue their work with their new account—for example, you might want to make the items the user added to their shopping cart before they signed up available in their new account's shopping cart. To do so, complete the following steps:

  1. When the user signs up, complete the sign-in flow for the user's authentication provider up to, but not including, calling one of the FIRAuth.signInWith methods. For example, get the user's Google ID token, Facebook access token, or email address and password.
  2. Get an FIRAuthCredential for the new authentication provider:

    Google Sign-In
      let authentication = user?.authentication,
      let idToken = authentication.idToken
    else {
    let credential = GoogleAuthProvider.credential(withIDToken: idToken,
                                                   accessToken: authentication.accessToken)
    GIDAuthentication *authentication = user.authentication;
    FIRAuthCredential *credential =
    [FIRGoogleAuthProvider credentialWithIDToken:authentication.idToken
    Facebook Login
    let credential = FacebookAuthProvider
      .credential(withAccessToken: AccessToken.current!.tokenString)
    FIRAuthCredential *credential = [FIRFacebookAuthProvider
        credentialWithAccessToken:[FBSDKAccessToken currentAccessToken].tokenString];
    Email-password sign-in
    let credential = EmailAuthProvider.credential(withEmail: email, password: password)
    FIRAuthCredential *credential =
        [FIREmailAuthProvider credentialWithEmail:email
  3. Pass the FIRAuthCredential object to the sign-in user's linkWithCredential:completion: method:

    Swift credential) { authResult, error in
      // ...
        [[FIRAuth auth].currentUser linkWithCredential:credential
        completion:^(FIRAuthDataResult *result, NSError *_Nullable error) {
      // ...

If the call to linkWithCredential:completion: succeeds, the user's new account can access the anonymous account's Firebase data.

Automatic clean-up

When you enable automatic clean-up in the Firebase console, anonymous accounts older than 30 days will be automatically deleted. Enabling this setting keeps your user database from filling with unused accounts. In projects with automatic clean-up enabled, anonymous authentication will not count toward usage limits or billing quotas.

  • Any anonymous accounts created after enabling automatic clean-up will be deleted 30 days after creation.
  • Anonymous accounts created before enabling automatic clean-up will be deleted around 30 days after enabling automatic clean-up.
  • If you turn automatic clean-up off, any anonymous accounts scheduled to be deleted will remain scheduled to be deleted.
  • If you "upgrade" an anonymous account by linking it to any sign-in method, the account will not get automatically deleted.

If you want to see how many users will be affected before you enable this feature, and you've upgraded your project to Firebase Authentication with Identity Platform, you can filter by is_anon in Cloud Logging.

Next steps

Now that users can authenticate with Firebase, you can control their access to data in your Firebase database using Firebase rules.