Xamarin Android cancel background notification after a certain time

As part of my assignment I want to remove a notification that has been received but not been interacted with after a certain amount of time. This means if the notification is still in the notification tray after this amount of time, the app will delete it automatically.

For foreground notifications this wasn’t the issue, as I applied the following code:

    void SendNotification(RemoteMessage remotemessage)
    {
        var intent = new Intent(this, typeof(MainActivity));
        intent.AddFlags(ActivityFlags.ClearTop);
        var pendingIntent = PendingIntent.GetActivity(this, 0, intent, PendingIntentFlags.OneShot);
        long[] pattern = { 100, 100, 100, 100 };

        var notificationBuilder = new Notification.Builder(this)
            .SetVibrate(pattern)
            .SetSmallIcon(Resource.Drawable.mhu2)
            .SetContentTitle(remotemessage.GetNotification().Title)
            .SetContentText(remotemessage.GetNotification().Body)
            .SetAutoCancel(true)
            .SetContentIntent(pendingIntent);

        NotificationManager notificationManager =
                (NotificationManager)GetSystemService(Context.NotificationService);

        int id = 0;

        notificationManager.Notify(id, notificationBuilder.Build());

        Handler handler = new Handler(Looper.MainLooper);

        long delayInMilliseconds = 5000;

        handler.PostDelayed(new Runnable(() => notificationManager.Cancel(id)), delayInMilliseconds);
    }

When a notification is received, it will automatically be removed after 5 seconds (debugging purposes). However, as we all know, notifications are not handled the same depending on the state of the app.

This code works for foreground apps, but will never be run when the app is in the background or killed. So when the user receives a notification when the app was not opened or in the background, the notification will not be removed.

I’ve tried to look into this and saw partial solutions by executing code when overriding the OnDestroy/OnStop/OnPause state, but that still won’t help to remove the notification when the app was never opened.

Any suggestions are greatly appreciated!