Authenticate Using Twitter on Android

You can let your users authenticate with Firebase using their Twitter accounts by integrating Twitter authentication into your app.

Before you begin

If you haven't already, add Firebase to your Android project.
In your project-level build.gradle file, make sure to include Google's Maven repository in both your buildscript and allprojects sections.
Add the dependency for the Firebase Authentication Android library to your module (app-level) Gradle file (usually app/build.gradle):
```
implementation 'com.google.firebase:firebase-auth:18.0.0'
```
Register your app as a developer application on Twitter and get your app's API Key and API Secret.
Enable Twitter Login:
1. In the Firebase console, open the Auth section.
2. On the Sign in method tab, enable the Twitter sign-in method and specify the API Key and API Secret you got from Twitter.
3. Then, make sure your Firebase OAuth redirect URI (e.g. my-app-12345.firebaseapp.com/__/auth/handler) is set as your Callback URL in your app's settings page on your Twitter app's config.

Authenticate with Firebase

In your sign-in activity's onCreate method, get the shared instance of the FirebaseAuth object:

Java

private FirebaseAuth mAuth;
// ...
// Initialize Firebase Auth
mAuth = FirebaseAuth.getInstance();TwitterLoginActivity.java

Kotlin

private lateinit var auth: FirebaseAuth
// ...
// Initialize Firebase Auth
auth = FirebaseAuth.getInstance()TwitterLoginActivity.kt

When initializing your Activity, check to see if the user is currently signed in:

Java

@Override
public void onStart() {
    super.onStart();
    // Check if user is signed in (non-null) and update UI accordingly.
    FirebaseUser currentUser = mAuth.getCurrentUser();
    updateUI(currentUser);
}TwitterLoginActivity.java

Kotlin

public override fun onStart() {
    super.onStart()
    // Check if user is signed in (non-null) and update UI accordingly.
    val currentUser = auth.currentUser
    updateUI(currentUser)
}TwitterLoginActivity.kt

Integrate Sign in with Twitter into your app by following the developer's documentation. At the end of the Twitter sign-in flow, you will receive an OAuth access token and an OAuth secret. You should have code in your Activity that looks something like this:

Java

private TwitterLoginButton mLoginButton;

// ...

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // ...
    mLoginButton = findViewById(R.id.buttonTwitterLogin);
    mLoginButton.setCallback(new Callback<TwitterSession>() {
        @Override
        public void success(Result<TwitterSession> result) {
            Log.d(TAG, "twitterLogin:success" + result);
            handleTwitterSession(result.data);
        }

        @Override
        public void failure(TwitterException exception) {
            Log.w(TAG, "twitterLogin:failure", exception);
            updateUI(null);
        }
    });
}

// ...

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    // Pass the activity result to the Twitter login button.
    mLoginButton.onActivityResult(requestCode, resultCode, data);
}TwitterLoginActivity.java

Kotlin

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    buttonTwitterLogin?.callback = object : Callback<TwitterSession>() {
        override fun success(result: Result<TwitterSession>) {
            Log.d(TAG, "twitterLogin:success$result")
            handleTwitterSession(result.data)
        }

        override fun failure(exception: TwitterException) {
            Log.w(TAG, "twitterLogin:failure", exception)
            updateUI(null)
        }
    }
}

// ...

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    super.onActivityResult(requestCode, resultCode, data)

    // Pass the activity result to the Twitter login button.
    loginButton!!.onActivityResult(requestCode, resultCode, data)
}TwitterLoginActivity.kt

After a user successfully signs in with Twitter, exchange the OAuth access token and OAuth secret for a Firebase credential, and authenticate with Firebase using the Firebase credential:

Java

private void handleTwitterSession(TwitterSession session) {
    Log.d(TAG, "handleTwitterSession:" + session);

    AuthCredential credential = TwitterAuthProvider.getCredential(
            session.getAuthToken().token,
            session.getAuthToken().secret);

    mAuth.signInWithCredential(credential)
            .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    if (task.isSuccessful()) {
                        // Sign in success, update UI with the signed-in user's information
                        Log.d(TAG, "signInWithCredential:success");
                        FirebaseUser user = mAuth.getCurrentUser();
                        updateUI(user);
                    } else {
                        // If sign in fails, display a message to the user.
                        Log.w(TAG, "signInWithCredential:failure", task.getException());
                        Toast.makeText(TwitterLoginActivity.this, "Authentication failed.",
                                Toast.LENGTH_SHORT).show();
                        updateUI(null);
                    }

                    // ...
                }
            });
}TwitterLoginActivity.java

Kotlin

private fun handleTwitterSession(session: TwitterSession) {
    Log.d(TAG, "handleTwitterSession:$session")

    val credential = TwitterAuthProvider.getCredential(
            session.authToken.token,
            session.authToken.secret)

    auth.signInWithCredential(credential)
            .addOnCompleteListener(this) { task ->
                if (task.isSuccessful) {
                    // Sign in success, update UI with the signed-in user's information
                    Log.d(TAG, "signInWithCredential:success")
                    val user = auth.currentUser
                    updateUI(user)
                } else {
                    // If sign in fails, display a message to the user.
                    Log.w(TAG, "signInWithCredential:failure", task.exception)
                    Toast.makeText(baseContext, "Authentication failed.",
                            Toast.LENGTH_SHORT).show()
                    updateUI(null)
                }

                // ...
            }
}TwitterLoginActivity.kt

If the call to signInWithCredential succeeds, you can use the returned FirebaseUser to proceed.

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 FirebaseUser 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:

Java

FirebaseAuth.getInstance().signOut();MainActivity.java

Kotlin

FirebaseAuth.getInstance().signOut()MainActivity.kt