ExzileGames.AndroidFcmBridge 1.0.25

AndroidFcmBridge

A Java bridge + C# interop library for Firebase Cloud Messaging (FCM) on .NET Android. Provides async token retrieval, topic subscriptions, and push message callbacks for re-engagement notifications.

Problem

FirebaseMessagingService must be subclassed in Java and registered in the Android manifest — it cannot be implemented in C# alone. Without a compiled Java subclass, FCM token refresh events and incoming push messages are never delivered to your app.

Solution

This library compiles a FirebaseMessagingService subclass (ExzileFcmService) directly into your Android project. It forwards token refreshes and incoming messages to your C# code via auto-generated JNI bindings, with no manual Java callback wiring required.

APIs Exposed

Setup

1. Add NuGet package

dotnet add package ExzileGames.AndroidFcmBridge

2. Add google-services.json

Place your google-services.json (from the Firebase Console) in the Android app project root:

<GoogleServicesJson Include="google-services.json" />

3. Register the service in AndroidManifest.xml

<service android:name="com.exzilegames.fcmbridge.ExzileFcmService"
         android:exported="false">
    <intent-filter>
        <action android:name="com.google.firebase.MESSAGING_EVENT" />
    </intent-filter>
</service>

4. Initialize in your Activity

using AndroidFcmBridge.Interop;

protected override void OnCreate(Bundle? savedInstanceState)
{
    base.OnCreate(savedInstanceState);

    var fcm = new AndroidFcmBridgeImpl(this);
    FcmBridgeManager.SetImplementation(fcm);
}

5. Use from shared code

using AndroidFcmBridge.Interop;

// Register listeners before calling GetTokenAsync to avoid missing the first refresh
FcmBridgeManager.SetTokenRefreshListener(token =>
{
    // Send updated token to your server
    Console.WriteLine($"New FCM token: {token}");
});

FcmBridgeManager.SetMessageListener(message =>
{
    Console.WriteLine($"Push received: {message.Title} — {message.Body}");
    foreach (var (key, value) in message.Data)
        Console.WriteLine($"  {key} = {value}");
});

// Retrieve current token
var result = await FcmBridgeManager.GetTokenAsync();
if (result.Success)
    Console.WriteLine($"FCM token: {result.Token}");

// Subscribe/unsubscribe topics
await FcmBridgeManager.SubscribeToTopicAsync("news");
await FcmBridgeManager.UnsubscribeFromTopicAsync("news");

License

MIT