[Activity(Label = "App",
              Icon = "@drawable/ic_launcher",
              Theme = "@style/splashscreen",
              MainLauncher = true,
              ScreenOrientation = ScreenOrientation.Portrait)]
    public class MainActivity : Xamarin.Forms.Platform.Android.FormsAppCompatActivity
    {

        protected override void OnCreate(Bundle bundle)
        {

            SetTheme(Resource.Style.MainTheme);

            TabLayoutResource = Resource.Layout.Tabbar;
            ToolbarResource = Resource.Layout.Toolbar;
            base.OnCreate(bundle);

            Forms.Init(this, bundle);

            LoadApplication(new App());
            StartBackgroundService();
            IsAppRunning = true;
        }

        private void StartBackgroundService() {
            StopService = false;
            RealtimeService.StopServiceEventHandler += StopServiceEventHandler;
            StartService(new Intent(Forms.Context, typeof(BackgroundRealtimeService)));
        }

        private void StopServiceEventHandler(object sender, object o) {
            if (StopService) {
                StopService(new Intent(Forms.Context, typeof(BackgroundRealtimeService)));
            }
        }


        protected override void OnDestroy()
        {
            IsAppRunning = false;
            base.OnDestroy();
        }
    }
}

[Service]
    public class BackgroundRealtimeService : Service
    {
        public async void Initialize() {

           // Service Code

        }


        public override void OnCreate() {
            base.OnCreate();
        }

        public override StartCommandResult OnStartCommand(Intent intent, StartCommandFlags flags, int startId) {

            new Task(Initialize).Start();
            return StartCommandResult.Sticky;
        }


        public override IBinder OnBind(Intent intent)
        {
            return null;
        }
    }
}