Authenticate Using Google Sign-In and Unity

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

Before you begin

Before you can use Firebase Authentication, you need to:

• Register your Unity project and configure it to use Firebase.

  • If your Unity project already uses Firebase, then it's already registered and configured for Firebase.

  • If you don't have a Unity project, you can download a sample app.

• Add the Firebase Unity SDK (specifically, FirebaseAuth.unitypackage) to your Unity project.

Note that adding Firebase to your Unity project involves tasks both in the Firebase console and in your open Unity project (for example, you download Firebase config files from the console, then move them into your Unity project).

Access the Firebase.Auth.FirebaseAuth class

Firebase.Auth.FirebaseAuth auth = Firebase.Auth.FirebaseAuth.DefaultInstance;

Authenticate with Firebase

1. Follow instructions for Android and iOS+ to get an ID token for the Google sign in.
2. After a user successfully signs in, exchange the access token for a Firebase credential, and authenticate with Firebase using the Firebase credential:

   Firebase.Auth.Credential credential =
       Firebase.Auth.GoogleAuthProvider.GetCredential(googleIdToken, googleAccessToken);
   auth.SignInAndRetrieveDataWithCredentialAsync(credential).ContinueWith(task => {
     if (task.IsCanceled) {
       Debug.LogError("SignInAndRetrieveDataWithCredentialAsync was canceled.");
       return;
     }
     if (task.IsFaulted) {
       Debug.LogError("SignInAndRetrieveDataWithCredentialAsync encountered an error: " + task.Exception);
       return;
     }
   
     Firebase.Auth.AuthResult result = task.Result;
     Debug.LogFormat("User signed in successfully: {0} ({1})",
         result.User.DisplayName, result.User.UserId);
   });

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 Firebase.Auth.FirebaseUser object:

  Firebase.Auth.FirebaseUser user = auth.CurrentUser;
  if (user != null) {
    string name = user.DisplayName;
    string email = user.Email;
    System.Uri photo_url = user.PhotoUrl;
    // 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 User.TokenAsync() instead.
    string uid = user.UserId;
  }

• 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():

auth.SignOut();