FirebaseUI is an open-source library that offers simple, customizable UI bindings on top of the core Firebase SDKs. It aims to eliminate boilerplate code and promote best practices (both user experience and security) for authentication.
A simple API is provided for drop-in user authentication which handles the flow of signing in users with email addresses and passwords, and federated identity providers such as Google Sign-In, and Facebook Login. It is built on top of Firebase Auth.
The best practices embodied in FirebaseUI aim to maximize sign-in and sign-up conversion for your app. It integrates with Smart Lock for Passwords to store and retrieve credentials, enabling automatic and single-tap sign-in to your app for returning users. It also handles tricky use cases like account recovery and account linking that are security sensitive and difficult to implement correctly using the base APIs provided by Firebase Auth.
FirebaseUI auth can be easily customized to fit with the rest of your app's visual style. As it is open source, you are also free to modify it to exactly fit your preferred user experience.
Equivalent FirebaseUI auth libraries are also available for iOS and Web.
As a pre-requisite, ensure your application is configured for use with Firebase: see the Firebase documentation. Then, add the FirebaseUI auth library dependency. If your project uses Gradle, add the dependency:
dependencies {
// ...
compile 'com.firebaseui:firebase-ui-auth:1.2.0'
}and add the Fabric repository
allprojects {
repositories {
// ...
maven { url 'https://maven.fabric.io/public' }
}
}In order to use either Google, Facebook or Twitter accounts with your app, ensure that these authentication methods are first configured in the Firebase console.
FirebaseUI client-side configuration for Google sign-in is then provided
automatically by the
google-services gradle plugin.
If support for Facebook Login is also required, define the
resource string facebook_application_id to match the application ID in
the Facebook developer dashboard:
<resources>
<!-- ... -->
<string name="facebook_application_id" translatable="false">APP_ID</string>
<!-- Facebook Application ID, prefixed by 'fb'. Enables Chrome Custom tabs. -->
<string name="facebook_login_protocol_scheme" translatable="false">fbAPP_ID</string>
</resources>If support for Twitter Sign-in is also required, define the resource strings
twitter_consumer_key and twitter_consumer_secret to match the values of your
Twitter app as reported by the Twitter application manager.
<resources>
<string name="twitter_consumer_key" translatable="false">YOURCONSUMERKEY</string>
<string name="twitter_consumer_secret" translatable="false">YOURCONSUMERSECRET</string>
</resources>
In addition, you must enable the "Request email addresses from users" permission in the "Permissions" tab of your Twitter app.
Before invoking the FirebaseUI authentication flow, your app should check whether a user is already signed in from a previous session:
FirebaseAuth auth = FirebaseAuth.getInstance();
if (auth.getCurrentUser() != null) {
// already signed in
} else {
// not signed in
}The entry point to the authentication flow is the
com.firebase.ui.auth.AuthUI class.
If your application uses the default FirebaseApp instance, an AuthUI
instance can be retrieved simply by calling AuthUI.getInstance().
If an alternative app instance is required, call
AuthUI.getInstance(app) instead, passing the appropriate FirebaseApp
instance.
If a user is not currently signed in, as can be determined by checking
auth.getCurrentUser() != null (where auth is the FirebaseAuth instance
associated with your FirebaseApp), then the sign-in process can be started by
creating a sign-in intent using AuthUI.SignInIntentBuilder. A builder instance
can be retrieved by calling createSignInIntentBuilder() on the retrieved
AuthUI instance.
The builder provides the following customization options for the authentication flow:
- The set of authentication providers can be specified.
- The terms of service URL for your app can be specified, which is included as a link in the small-print of the account creation step for new users. If no terms of service URL is provided, the associated small-print is omitted.
- A custom theme can be specified for the flow, which is applied to all the activities in the flow for consistent colors and typography.
If no customization is required, and only email authentication is required, the sign-in flow can be started as follows:
// Choose an arbitrary request code value
private static final int RC_SIGN_IN = 123;
// ...
startActivityForResult(
// Get an instance of AuthUI based on the default app
AuthUI.getInstance().createSignInIntentBuilder().build(),
RC_SIGN_IN);To kick off the FirebaseUI sign in flow, call startActivityForResult(...) on the sign in Intent you built. The second parameter (RC_SIGN_IN) is a request code you define to identify the request when the result is returned to your app in onActivityResult(...). See the response codes section below for more details on receiving the results of the sign in flow.
You can enable sign-in providers like Google Sign-In or Facebook Log In by calling the
setProviders method:
startActivityForResult(
AuthUI.getInstance()
.createSignInIntentBuilder()
.setProviders(Arrays.asList(new AuthUI.IdpConfig.Builder(AuthUI.EMAIL_PROVIDER).build(),
new AuthUI.IdpConfig.Builder(AuthUI.GOOGLE_PROVIDER).build(),
new AuthUI.IdpConfig.Builder(AuthUI.FACEBOOK_PROVIDER).build(),
new AuthUI.IdpConfig.Builder(AuthUI.TWITTER_PROVIDER).build()))
.build(),
RC_SIGN_IN);If a terms of service URL and a custom theme are required:
startActivityForResult(
AuthUI.getInstance()
.createSignInIntentBuilder()
.setProviders(...)
.setTosUrl("https://superapp.example.com/terms-of-service.html")
.setTheme(R.style.SuperAppTheme)
.build(),
RC_SIGN_IN);By default, FirebaseUI uses Smart Lock for Passwords
to store the user's credentials and automatically sign users into your app on subsequent attempts.
Using Smart Lock is recommended to provide the best user experience, but in some cases you may want
to disable Smart Lock for testing or development. To disable Smart Lock, you can use the
setIsSmartLockEnabled method when building your sign-in Intent:
startActivityForResult(
AuthUI.getInstance()
.createSignInIntentBuilder()
.setIsSmartLockEnabled(false)
.build(),
RC_SIGN_IN);It is often desirable to disable Smart Lock in development but enable it in production. To achieve
this, you can use the BuildConfig.DEBUG flag to control Smart Lock:
startActivityForResult(
AuthUI.getInstance()
.createSignInIntentBuilder()
.setIsSmartLockEnabled(!BuildConfig.DEBUG)
.build(),
RC_SIGN_IN);The authentication flow provides several response codes of which the most common are as follows:
ResultCodes.OK if a user is signed in, ResultCodes.CANCELLED if the user manually canceled the sign in,
ResultCodes.NO_NETWORK if sign in failed due to a lack of network connectivity,
and ResultCodes.UNKNOWN_ERROR for all other errors.
Typically, the only recourse for most apps if sign in fails is to ask
the user to sign in again later, or proceed with anonymous sign-in if supported.
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
// RC_SIGN_IN is the request code you passed into startActivityForResult(...) when starting the sign in flow.
if (requestCode == RC_SIGN_IN) {
IdpResponse response = IdpResponse.fromResultIntent(data);
// Successfully signed in
if (resultCode == ResultCodes.OK) {
startActivity(SignedInActivity.createIntent(this, response));
finish();
return;
} else {
// Sign in failed
if (response == null) {
// User pressed back button
showSnackbar(R.string.sign_in_cancelled);
return;
}
if (response.getErrorCode() == ErrorCodes.NO_NETWORK) {
showSnackbar(R.string.no_internet_connection);
return;
}
if (response.getErrorCode() == ErrorCodes.UNKNOWN_ERROR) {
showSnackbar(R.string.unknown_error);
return;
}
}
showSnackbar(R.string.unknown_sign_in_response);
}
}Alternatively, you can register a listener for authentication state changes; see the Firebase Auth documentation for more information.
To retrieve the ID token that the IDP returned, you can extract an IdpResponse from the result
Intent.
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == ResultCodes.OK) {
IdpResponse idpResponse = IdpResponse.fromResultIntent(data);
startActivity(new Intent(this, WelcomeBackActivity.class)
.putExtra("my_token", idpResponse.getIdpToken()));
}
}Twitter also returns an AuthToken Secret which can be accessed with idpResponse.getIdpSecret().
With the integrations provided by AuthUI, signing out a user is a multi-stage process:
- The user must be signed out of the FirebaseAuth instance.
- Smart Lock for Passwords must be instructed to disable automatic sign-in, in order to prevent an automatic sign-in loop that prevents the user from switching accounts.
- If the current user signed in using either Google or Facebook, the user must also be signed out using the associated API for that authentication method. This typically ensures that the user will not be automatically signed-in using the current account when using that authentication method again from the authentication method picker, which would also prevent the user from switching between accounts on the same provider.
In order to make this process easier, AuthUI provides a simple signOut method
to encapsulate this behavior. The method returns a Task which is marked
completed once all necessary sign-out operations are completed:
public void onClick(View v) {
if (v.getId() == R.id.sign_out) {
AuthUI.getInstance()
.signOut(this)
.addOnCompleteListener(new OnCompleteListener<Void>() {
public void onComplete(@NonNull Task<Void> task) {
// user is now signed out
startActivity(new Intent(MyActivity.this, SignInActivity.class));
finish();
}
});
}
}With the integrations provided by FirebaseUI Auth, deleting a user is a multi-stage process:
- The user must be deleted from Firebase Auth.
- Smart Lock for Passwords must be told to delete any existing Credentials for the user, so that they are not automatically prompted to sign in with a saved credential in the future.
This process is encapsulated by the AuthUI.delete() method, which returns a Task representing
the entire operation:
AuthUI.getInstance()
.delete(this)
.addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task) {
if (task.isSuccessful()) {
// Deletion succeeded
} else {
// Deletion failed
}
}
});The authentication flow implemented on Android is more complex than on other platforms, due to the availability of Smart Lock for Passwords. It is represented in the following diagram:
To provide customization of the visual style of the activities that implement the flow, a new theme can be declared. Standard material design color and typography properties will take effect as expected. For example, to define a green theme:
<style name="GreenTheme" parent="FirebaseUI">
<item name="colorPrimary">@color/material_green_500</item>
<item name="colorPrimaryDark">@color/material_green_700</item>
<item name="colorAccent">@color/material_purple_a700</item>
<item name="colorControlNormal">@color/material_green_500</item>
<item name="colorControlActivated">@color/material_lime_a700</item>
<item name="colorControlHighlight">@color/material_green_a200</item>
<item name="android:windowBackground">@color/material_green_50</item>
</style>With associated colors:
<color name="material_green_50">#E8F5E9</color>
<color name="material_green_500">#4CAF50</color>
<color name="material_green_700">#388E3C</color>
<color name="material_green_a200">#69F0AE</color>
<color name="material_lime_a700">#AEEA00</color>
<color name="material_purple_a700">#AA00FF</color>This would then be used in the construction of the sign-in intent:
startActivityForResult(
AuthUI.getInstance(this).createSignInIntentBuilder()
// ...
.setTheme(R.style.GreenTheme)
.build());Your application theme could also simply be used, rather than defining a new one.
If you wish to change the string messages, the existing strings can be easily overridden by name in your application. See the built-in strings.xml and simply redefine a string to change it, for example:
<resources>
<!-- was "Signing up..." -->
<string name="progress_dialog_signing_up">Creating your shiny new account...</string>
</resources>By default, FirebaseUI requests the email and profile scopes when using Google Sign-In. If you
would like to request additional scopes from the user, call setPermissions on the
AuthUI.IdpConfig.Builder when initializing FirebaseUI.
// For a list of all scopes, see:
// https://developers.google.com/identity/protocols/googlescopes
AuthUI.IdpConfig googleIdp = new AuthUI.IdpConfig.Builder(AuthUI.GOOGLE_PROVIDER)
.setPermissions(Arrays.asList(Scopes.GAMES))
.build();
startActivityForResult(
AuthUI.getInstance()
.createSignInIntentBuilder()
.setProviders(Arrays.asList(new IdpConfig.Builder(AuthUI.EMAIL_PROVIDER).build(),
googleIdp,
new IdpConfig.Builder(AuthUI.FACEBOOK_PROVIDER).build()))
.build(),
RC_SIGN_IN);By default, FirebaseUI requests the email and public_profile permissions when initiating
Facebook Login. If you would like to request additional permissions from the user, call
setPermissions on the AuthUI.IdpConfig.Builder when initializing FirebaseUI.
// For a list of permissions see:
// https://developers.facebook.com/docs/facebook-login/android
// https://developers.facebook.com/docs/facebook-login/permissions
AuthUI.IdpConfig facebookIdp = new AuthUI.IdpConfig.Builder(AuthUI.FACEBOOK_PROVIDER)
.setPermissions(Arrays.asList("user_friends"))
.build();
startActivityForResult(
AuthUI.getInstance()
.createSignInIntentBuilder()
.setProviders(Arrays.asList(new AuthUI.IdpConfig.Builder(AuthUI.EMAIL_PROVIDER).build(),
facebookIdp))
.build(),
RC_SIGN_IN);Twitter permissions can only be configured through Twitter's developer console.