How to create a app where that app services always runs in background even if the app is closed in Xamarin (Android)?

Question

I am creating an application in Xamarin using visual studio,where that app services always should be running in background even if the app is closed and that service should send notification in a interval. If that app is closed by the system(in the condition when it is taking more memory space) then it should restart the services by showing the status as "0 process and 0 service Restarting.." under running services list in Settings.

Can anyone help me how to achieve that having some reference of sample project.

In BackgroundService.cs

[Service]
public class BackgroundService : Service
{
    const int SERVICE_RUNNING_NOTIFICATION_ID = 123;
    const string NOTIFICATION_CHANNEL_ID = "com.company.app.channel";
    public override StartCommandResult OnStartCommand(Intent intent, StartCommandFlags flags, int startId)
    {
        Log.Debug("service", "Service Started");
        // Check if device is running Android 8.0 or higher and call StartForeground() if so
        if (Build.VERSION.SdkInt >= BuildVersionCodes.O)
        {
            var notification = new NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID)
                               .SetContentTitle(Resources.GetString(Resource.String.app_name))
                               .SetContentText(Resources.GetString(Resource.String.notification_text))
                               .SetSmallIcon(Resource.Drawable.notification_icon_background)
                               .SetOngoing(true)
                               .Build();

            var notificationManager =
                GetSystemService(NotificationService) as NotificationManager;

            var chan = new NotificationChannel(NOTIFICATION_CHANNEL_ID, "On-going Notification", NotificationImportance.Min);

            notificationManager.CreateNotificationChannel(chan);

            StartForeground(SERVICE_RUNNING_NOTIFICATION_ID, notification);
        }
        return StartCommandResult.NotSticky;

    }

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

    public override void OnTaskRemoved(Intent rootIntent)
    {
        Intent restartServiceIntent = new Intent(this, this.Class);
        restartServiceIntent.SetPackage(this.PackageName);
        Log.Debug("service", "Service Restarted");

        PendingIntent restartServicePendingIntent = PendingIntent.GetService(this, 1, restartServiceIntent, PendingIntentFlags.OneShot);
        AlarmManager alarmService = (AlarmManager)this.GetSystemService(Context.AlarmService);
        alarmService.Set(
            AlarmType.ElapsedRealtime,
           SystemClock.ElapsedRealtime() + 1000,
            restartServicePendingIntent);
        base.OnTaskRemoved(rootIntent);
    }

}

Updtaed MainActivity.cs

public class MainActivity : AppCompatActivity
{
    String alarm = Android.Content.Context.AlarmService;
    const string NOTIFICATION_CHANNEL_ID = "com.companyname.ServiceSample3";
    protected override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);
        SetContentView(Resource.Layout.abc_activity_chooser_view);

        Android.Support.V7.Widget.Toolbar toolbar = FindViewById<Android.Support.V7.Widget.Toolbar>(Resource.Id.toolbar);
        SetSupportActionBar(toolbar);

        //var alarmIntent = new Intent(this, typeof(AlarmReceiver));
        //alarmIntent.PutExtra("title", "Hello");
        //alarmIntent.PutExtra("message", "World!");

        Intent intent = new Intent(NOTIFICATION_CHANNEL_ID);
        intent.SetClass(this, typeof(AlarmReceiver));

        var pending = PendingIntent.GetBroadcast(this, 0, intent, PendingIntentFlags.UpdateCurrent);

        var alarmManager = GetSystemService(AlarmService).JavaCast<AlarmManager>();
        alarmManager.SetRepeating(AlarmType.ElapsedRealtime, DateTime.Now.Millisecond, 5 * 100, pending);


    }
}

Thanks in advance.

Just check this out https://forums.xamarin.com/discussion/112541/background-service-get-gps-location-every-x-minutes — FreakyAli, Mar 19 '19 at 11:32
@G.Hakim I already went through this backgroundLocationDemo but there also once when I remove app from recent app tray then my service is stopped. Like how whatsapp is working,service is killed when there is load in memory but once memory is free again automatically service is started.This is how i want my app should work. Do have any reference. — shweta, Mar 19 '19 at 13:26
@ramya br I checked your answer But when cleared from recent app tray the Service is stopped — shweta, Mar 20 '19 at 09:32
It is working fine for me ..If clear the app also service will be running..Please check you did exact what I wrote — ramya br, Mar 20 '19 at 09:38
Use other than mi phones.It has more security related things.This may kill the service. — ramya br, Mar 20 '19 at 09:54
@ramya br I tried in Motorola MotoE2 ,then also after clearing from cache,from running apps it is not showing. — shweta, Mar 20 '19 at 09:59
Ya.It's working in Motorola .I will check in some other phone.Currently not supporting in MI. Thanks a lot for your help. — shweta, Mar 20 '19 at 10:06
@ramya br it is not working in Motorola Moto G(Android 8.1).Do you know the reason.Which Android version you tried? — shweta, Mar 20 '19 at 10:18
please check this link https://stackoverflow.com/questions/46304839/android-8-0-oreo-alarmmanager-with-broadcast-receiver-and-implicit-broadcast-ban — ramya br, Mar 20 '19 at 10:30
in the activity where you used for the intent for Alarm Reciever — ramya br, Mar 20 '19 at 10:42
I updated code MainActivity.cs.Can u tell me where i am wrong because it's still not working in Android 8.1(Motorola moto g) — shweta, Mar 20 '19 at 11:08
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/190359/discussion-between-ramya-br-and-shweta). — ramya br, Mar 20 '19 at 11:14

ramya br · Answer 1 · 2019-03-20T06:51:30.743

Please refer the below sample.You can use alarm manager for restarting the service.

Please follow the steps.

Step 1 : Create BroadcastReceiver

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;

namespace AlarmManagerApp
{
    [BroadcastReceiver(Enabled = true)]
    [IntentFilter(new[] { Android.Content.Intent.ActionBootCompleted })]
    class AlarmReceiver : BroadcastReceiver
    {
        Context context;
        public override void OnReceive(Context context, Intent intent)
        {
            this.context = context;
            Toast.MakeText(context,"Recieved",ToastLength.Long).Show();
            Intent background = new Intent(context, typeof(BackgroundService));
            context.StartService(background);

        }
    }
}

Step 2: Add AlarmManager in the MainActivity where you want to call the service

namespace AlarmManagerApp
{
    [Activity(Label = "@string/app_name", Theme = "@style/AppTheme.NoActionBar", MainLauncher = true)]
    public class MainActivity : AppCompatActivity
    {
        String alarm = Context.AlarmService;
        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);
            SetContentView(Resource.Layout.activity_main);

            Android.Support.V7.Widget.Toolbar toolbar = FindViewById<Android.Support.V7.Widget.Toolbar>(Resource.Id.toolbar);
            SetSupportActionBar(toolbar);

            var alarmIntent = new Intent(this, typeof(AlarmReceiver));
            alarmIntent.PutExtra("title", "Hello");
            alarmIntent.PutExtra("message", "World!");

            var pending = PendingIntent.GetBroadcast(this, 0, alarmIntent, PendingIntentFlags.UpdateCurrent);

            var alarmManager = GetSystemService(AlarmService).JavaCast<AlarmManager>();
            alarmManager.SetRepeating(AlarmType.ElapsedRealtime,DateTime.Now.Millisecond,  5 * 100, pending);


          }
   }

Step 3: Add you Service

namespace AlarmManagerApp
{
    [Service]
    public class BackgroundService : Service
    {
        public override void OnCreate()
        {
            base.OnCreate();

        }

        public override StartCommandResult OnStartCommand(Intent intent, StartCommandFlags flags, int startId)
        {
            Log.Debug("service","Service Started");
            //init the handler in oncreate
            System.Timers.Timer Timer1 = new System.Timers.Timer();
            Timer1.Start();
            Timer1.Interval = 3000;
            int a = 0;
            Timer1.Enabled = true;
            //Timer1.Elapsed += OnTimedEvent;
            Timer1.Elapsed += (object sender, System.Timers.ElapsedEventArgs e) =>
            {
                Timer1.Stop();
                Timer1.Start();
                a++;
               //Delete time since it will no longer be used.
                Timer1.Dispose();
            };
            Timer1.Start();

            return StartCommandResult.Sticky;
        }

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

        public override void OnTaskRemoved(Intent rootIntent)
        {
            Intent restartServiceIntent = new Intent(this, this.Class);
            restartServiceIntent.SetPackage(this.PackageName);
            Log.Debug("service", "Service Restarted");

            PendingIntent restartServicePendingIntent = PendingIntent.GetService(this, 1, restartServiceIntent, PendingIntentFlags.OneShot);
            AlarmManager alarmService = (AlarmManager)this.GetSystemService(Context.AlarmService);

            alarmService.SetRepeating(AlarmType.RtcWakeup, SystemClock.CurrentThreadTimeMillis(), 30 * 1000, restartServicePendingIntent);
            NotificationManager notificationManager =
                (NotificationManager)GetSystemService(NotificationService);

            Notification.Builder builder = new Notification.Builder(this);
            Intent notificationIntent = new Intent(this, typeof(MainActivity));
            PendingIntent contentIntent = PendingIntent.GetActivity(this, 0, notificationIntent, 0);

            //set
            builder.SetContentIntent(contentIntent);
            builder.SetSmallIcon(Resource.Mipmap.ic_launcher);
            builder.SetContentText("Contents");
            builder.SetContentTitle("title");
            builder.SetAutoCancel(true);
            builder.SetDefaults(NotificationDefaults.All);


            notificationManager.Notify(1, builder.Build());

            base.OnTaskRemoved(rootIntent);
        }
    }
}

This works also if app is closed and device restarted.

StartService(new Intent(this, typeof(BackgroundService))); I have to call this inside OnCreate Method??? — shweta, Mar 19 '19 at 09:37
If you want to start the service in onCreate you can call that — ramya br, Mar 19 '19 at 09:39
My service is running.But when i m clearing the cache of my mobile ,service is not running. — shweta, Mar 19 '19 at 09:58
Above code is not working on Adndroid version 8.1.Can u please once look at it. I changed the StartService to StartForegroundService in OnRecieve Method(Restarter class) but then also it's not working. — shweta, Mar 20 '19 at 12:54
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/190381/discussion-between-ramya-br-and-shweta). — ramya br, Mar 20 '19 at 17:14
Can you go through once, what changes required to make the service run in background having android version 8.1 — shweta, Mar 21 '19 at 05:00

How to create a app where that app services always runs in background even if the app is closed in Xamarin (Android)?

1 Answers1