Minimal FCM Push Messaging for .NET MAUI (RC3)

README

* Setup Firebase project like normal and add google-services.json (make sure Build action is set to GoogleServicesJson)
* Nugets required for MAUI project file (later versions don't work)

    <ItemGroup Condition="'$(TargetFramework)' == 'net6.0-android'">
        <PackageReference Include="Xamarin.Firebase.Iid" Version="121.1.0" />
        <PackageReference Include="Xamarin.Firebase.Messaging" Version="122.0.0" />
        <PackageReference Include="Xamarin.Google.Dagger" Version="2.39.1" />
        <PackageReference Include="Xamarin.GooglePlayServices.Base" Version="117.6.0.5" />
    </ItemGroup>
    

FCMService.cs

using Android.App;
using Android.Content;
using AndroidX.Core.App;
using Firebase.Messaging;

namespace FCMApp.Android;

[Service(Exported = false)]
[IntentFilter(new[] { "com.google.firebase.MESSAGING_EVENT" })]
public class FCMService : FirebaseMessagingService
{
    public override void OnMessageReceived(RemoteMessage message)
    {
        RemoteMessage.Notification notification = message.GetNotification();

        IDictionary<string, string> data = message.Data;
        string body = "";
        string title = "";

        if (data != null && data.ContainsKey("body") && data.ContainsKey("title"))
        {
            body = data["body"];
            title = data["title"];
        }
        else if (notification != null)
        {
            body = message.GetNotification().Body;
            title = message.GetNotification().Title;
        }
        if (!string.IsNullOrEmpty(body) && !string.IsNullOrEmpty(title))
        {
            // TODO: Manage this message (we get here only when app is in foreground)
        }
    }

}

IMessagingService.cs

namespace FCMApp;

public interface IMessagingService
{
    string GetToken();
    bool IsMessagingAvailable();
    void SetNewTokenCallback(Action<string> token_callback);
}
    

MessagingService.Android.cs

using Android.Gms.Common;
using Android.Gms.Tasks;
using Firebase.Iid;

namespace FCMApp;

public partial class MessagingService
{
    public partial bool IsMessagingAvailable() => GoogleApiAvailability.Instance.IsGooglePlayServicesAvailable(Android.App.Application.Context) == ConnectionResult.Success;
    public partial string GetToken() => FirebaseInstanceId.Instance.Token;
    public partial void SetNewTokenCallback(Action<string> token_callback)
    {
        if (token_callback == null)
            throw new InvalidOperationException("Callback cannot be null");
        
        if (GetToken() != null)
            token_callback(GetToken());
        else
            FirebaseInstanceId.Instance.GetInstanceId().AddOnSuccessListener(new OnTokenListener((token) => token_callback(token)));
    }
}

public class OnTokenListener : Java.Lang.Object, IOnSuccessListener
{
    Action<string> _callback;
    public OnTokenListener(Action<string> success_callback) => _callback = success_callback;
    public void OnSuccess(Java.Lang.Object result) => _callback?.Invoke(FirebaseInstanceId.Instance.Token);
}

MessagingService.cs

namespace FCMApp;

public partial class MessagingService : IMessagingService
{
    public partial string GetToken();
    public partial bool IsMessagingAvailable();
    public partial void SetNewTokenCallback(Action<string> token_callback);
}

@maurobernal
Replace the deprecated FirebaseInstanceId with FirebaseMessaging.

- FirebaseInstanceId.Instance.Token -> (string)FirebaseMessaging.Instance.GetToken().Result
- FirebaseInstanceId.Instance.GetInstanceId().AddOnSuccessListener(... -> FirebaseMessaging.Instance.GetToken().AddOnSuccessListener(...
- .Invoke(FirebaseInstanceId.Instance.Token) -> .Invoke((string)FirebaseMessaging.Instance.GetToken()

I have a clarifying question. How can I send a push inside my application to a user via FCM using the Messaging Service or FCMService? Please give examples

do you have working MAUI example for android?