bg-service.cs

/// <summary>
/// Android Native Background Service
/// </summary>
[Service]
public class BackgroundService : Service
{
    #region Fields
    
    /// <summary>
    /// The Id of the Service
    /// </summary>
    private const int SERVICE_ID = 7070;

    /// <summary>
    /// The string identifier for the service notification
    /// </summary>
    private const string SERVICE_NOTIFICATION_CHANNEL_ID = "7071";

    /// <summary>
    /// Background Worker
    /// </summary>
    private readonly IBackgroundWorker _backgroundWorker;

    #endregion Fields
    
    #region Contstoctors

    public BackgroundService()
    {
        _backgroundWorker = Mvx.IoCProvider.Resolve<IBackgroundWorker>();
    }
    
    #endregion Contstoctors
    
    #region Public Methods
    
    public override IBinder OnBind(Intent intent)
    {
        //  This service is not bindable by an external app so
        //  return null
        return null;
    }

    /// <summary>
    /// On Start Service Command
    /// </summary>
    /// <returns>Start Command Result</returns>
    [return: GeneratedEnum]
    public override StartCommandResult OnStartCommand(Intent intent, [GeneratedEnum] StartCommandFlags flags, int startId)
    {
        _backgroundWorker.WorkerStopped += BackgroundWorkerOnWorkerStopped;
        //  Build the notification for the foreground service
        var notification = BuildNotification();
        StartForeground(SERVICE_ID, notification);
        
        _ = Task.Run(_backgroundWorker.BackgroundWork);

        //  Return a sticky result so that the service remains running
        return StartCommandResult.Sticky;
    }

    #endregion Public Methods
    
    #region Private Methods

    /// <summary>
    /// Background Worker on Worker Stopped
    /// </summary>
    private void BackgroundWorkerOnWorkerStopped(object sender, EventArgs e)
    {
        _backgroundWorker.WorkerStopped -= BackgroundWorkerOnWorkerStopped;
        StopForeground(removeNotification:true);
        StopSelf();
    }
    
    /// <summary>
    /// Build Service Notification Tile
    /// </summary>
    /// <returns>Service Notification Tile</returns>
    private Notification BuildNotification()
    {
        // Building intent
        var intent = new Intent(Application.Context, typeof(MainActivity));
        intent.AddFlags(ActivityFlags.NoUserAction);
        intent.PutExtra("Title", "Message");

        var pendingIntent = PendingIntent.GetActivity(Application.Context, 0, intent, PendingIntentFlags.UpdateCurrent);

        var notificationBuilder = new NotificationCompat.Builder(Application.Context, SERVICE_NOTIFICATION_CHANNEL_ID)
            .SetContentTitle(AppResources.Notification_Title)
            .SetContentText(AppResources.Notification_Text)
            .SetSmallIcon(Resource.Drawable.icon)
            .SetColor(ResourcesCompat.GetColor(Application.Context.Resources, Resource.Color.colorAccent, null))
            .SetOngoing(true)
            .SetContentIntent(pendingIntent);

        // Building channel if API version is 26 or above
        if (Build.VERSION.SdkInt >= BuildVersionCodes.O)
        {
            var notificationChannel = new NotificationChannel(SERVICE_NOTIFICATION_CHANNEL_ID, "MaczDostawca", NotificationImportance.Low);
            notificationChannel.Importance = NotificationImportance.Low;
            notificationChannel.EnableLights(true);
            notificationChannel.EnableVibration(false);
            notificationChannel.SetShowBadge(true);

            if (Application.Context.GetSystemService(NotificationService) is NotificationManager notificationManager)
            {
                notificationBuilder.SetChannelId(SERVICE_NOTIFICATION_CHANNEL_ID);
                notificationManager.CreateNotificationChannel(notificationChannel);
            }
        }

        return notificationBuilder.Build();
    }

    #endregion Private Methods 
}