Google Sign-In Unity Plugin

Copyright (c) 2017 Google Inc. All rights reserved.

Overview

Google Sign-In API plugin for Unity game engine. Works with Android and iOS. This plugin exposes the Google Sign-In API within Unity. This is specifically intended to be used by Unity projects that require OAuth ID tokens or server auth codes.

It is cross-platform, supporting both Android and iOS.

See Google Sign-In for Android for more information.

Configuring the application on the API Console

To authenticate you need to create credentials on the API console for your application. The steps to do this are available on Google Sign-In for Android or as part of Firebase configuration. In order to access ID tokens or server auth codes, you also need to configure a web client ID.

How to build the sample

Get a Google Sign-In configuration file

This file contains the client-side information needed to use Google Sign-in. The details on how to do this are documented on the Developer website.

Once you have the configuration file, open it in a text editor. In the middle of the file you should see the oauth_client section:

      "oauth_client": [
        {
          "client_id": "411000067631-hmh4e210xxxxxxxxxx373t3icpju8ooi.apps.googleusercontent.com",
          "client_type": 3
        },
        {
          "client_id": "411000067631-udra361txxxxxxxxxx561o9u9hc0java.apps.googleusercontent.com",
          "client_type": 1,
          "android_info": {
            "package_name": "com.your.package.name.",
            "certificate_hash": "7ada045cccccccccc677a38c91474628d6c55d03"
          }
        }
      ]

There are 3 values you need for configuring your Unity project:

1. The Web client ID. This is needed for generating a server auth code for your backend server, or for generating an ID token. This is the client_id value for the oauth client with client_type == 3.
2. The package_name. The client entry with client_type == 1 is the Android client. The package_name must be entered in the Unity player settings.
3. The keystore used to sign your application. This is configured in the publishing settings of the Android Player properties in the Unity editor. This must be the same keystore used to generate the SHA1 fingerprint when creating the application on the console. NOTE: The configutation file does not reference the keystore, you need to keep track of this yourself.

Create a new project and import the plugin

Create a new Unity project and import the GoogleSignIn-1.0.0.unitypackage (or the latest version). This contains native code, C# Unity code needed to call the Google Sign-In API for both Android and iOS.

Import the sample scene

Import the GoogleSignIn-sample.unitypackage which contains the sample scene and scripts. This package is not needed if you are integrating Google Sign-in into your own application.

Configure the web client id

1. Open the sample scene in Assets/SignInSample/MainScene.
2. Select the Canvas object in the hierarchy and enter the web client id in the SignInSampleScript component.

Building for Android

1. Under Build Settings, select Android as the target platform.
2. Set the package name in the player settings to the package_name you found in the configuration file.
3. Select the keystore file, the key alias, and passwords.
4. Resolve the Google Play Services SDK dependencies by selecting from the menu: Assets/Play Services Resolver/Android Resolver/Resolve. This will add the required .aar files to your project in Assets/Plugins/Android.

Building for iOS

For iOS, follow the instructions for creating a GoogleService-Info.plist file on https://developers.google.com/identity/sign-in/ios/start-integrating.

In Unity, after switching to the iOS player, make sure to run the Play Services Resolver. This will add the required frameworks and libraries to the XCode project via CocoPods.

After generating the XCode project from Unity, download the GoogleService-Info.plist file from the Google Developers website and add it to your XCode project.

Using the Games Profile to sign in on Android

To use the Play Games Services Gamer profile when signing in, you need to edit the dependencies in Assets/GoogleSignIn/Editor/GoogleSignInDependencies.xml.

Uncomment the play-services-games dependency and re-run the resolution.

Using this plugin with Firebase Auth

Follow the instructions to use Firebase Auth with Credentials on the Firebase developer website.

Make sure to copy the google-services.json and/or GoogleService-Info.plist to your Unity project.

Then to use Google SignIn with Firebase Auth, you need to request an ID token when authenticating. The steps are:

1. Configure Google SignIn to request an id token and set the web client id as described above.
2. Call SignIn() (or SignInSilently()).
3. When handling the response, use the ID token to create a Firebase Credential.
4. Call Firebase Auth method SignInWithCredential().

    GoogleSignIn.Configuration = new GoogleSignInConfiguration {
      RequestIdToken = true,
      // Copy this value from the google-service.json file.
      // oauth_client with type == 3
      WebClientId = "1072123000000-iacvb7489h55760s3o2nf1xxxxxxxx.apps.googleusercontent.com"
    };

    Task<GoogleSignInUser> signIn = GoogleSignIn.DefaultInstance.SignIn ();

    TaskCompletionSource<FirebaseUser> signInCompleted = new TaskCompletionSource<FirebaseUser> ();
    signIn.ContinueWith (task => {
      if (task.IsCanceled) {
        signInCompleted.SetCanceled ();
      } else if (task.IsFaulted) {
        signInCompleted.SetException (task.Exception);
      } else {

        Credential credential = Firebase.Auth.GoogleAuthProvider.GetCredential (((Task<GoogleSignInUser>)task).Result.IdToken, null);
        auth.SignInWithCredentialAsync (credential).ContinueWith (authTask => {
          if (authTask.IsCanceled) {
            signInCompleted.SetCanceled();
          } else if (authTask.IsFaulted) {
            signInCompleted.SetException(authTask.Exception);
          } else {
            signInCompleted.SetResult(((Task<FirebaseUser>)authTask).Result);
          }
        });
      }
    });

Building the Plugin

To build the plugin run ./gradlew -PlintAbortOnError build_all. This builds the support aar library with lint warnings as errors and packages the plugin into a .unitypackage file. It also packages the sample scene and script in a separate package.

There's also a shortcut for linux/mac: ./build_all.

Potential GOTCHAS:

• build.gradle makes an assumption about the Unity version AND the path to the Unity executable. If this is not accurate, you can either modify the file directly or set up an environment variable called "UNITY_EXE" that contains the path to Unity.
• The build script uses system installed C++ compiler, CMake, and Android SDK tools. If you don't have any of these, you might run into problems.

Questions? Problems?

Post questions to this Github project.