Keep task working when the app is in the background - xamarin

Question

I'm coding a map tracking app on Xamarin forms. I'm using async tasks(with Device.StartTimer) to keep track of the location and another task for counter timer, but when I need to open another app, like a music app or whatever the app can't keep track while it is in the background. All tasks are stopping when I send the app in the background. When I start the app again, the tasks are not continued.
I just need to keep working while app running.
How could this be done?

Answer 1

You should use background task in this case, which is running outside the life cycle of the application. You can find more information here Xamarin background tasks

Answer 2

Due to Background Execution Limits in Android 8.0 or later, Normal service will be killed when in the Background.
In the Android 8.0 or later, I suggest you to achieve a foreground service to achieve that( receive higher priority than a "regular" service and a foreground service must provide a Notification that Android will display as long as the service is running).
You can use dependence service to open a foreground service in xamarin forms.
IService.cs create a interface for android to start service.
public interface IService
{
void Start();
}
Then achieved DependentService to start a Foreground Service.
DependentService.cs
[assembly: Xamarin.Forms.Dependency(typeof(DependentService))]
namespace TabGuesture.Droid
{
[Service]
public class DependentService : Service, IService
{
public void Start()
{
var intent = new Intent(Android.App.Application.Context,
typeof(DependentService));
if (Android.OS.Build.VERSION.SdkInt >= Android.OS.BuildVersionCodes.O)
{
Android.App.Application.Context.StartForegroundService(intent);
}
else
{
Android.App.Application.Context.StartService(intent);
}
}
public override IBinder OnBind(Intent intent)
{
return null;
}
public const int SERVICE_RUNNING_NOTIFICATION_ID = 10000;
public override StartCommandResult OnStartCommand(Intent intent,
StartCommandFlags flags, int startId)
{
// From shared code or in your PCL
CreateNotificationChannel();
string messageBody = "service starting";
var notification = new Notification.Builder(this, "10111")
.SetContentTitle(Resources.GetString(Resource.String.app_name))
.SetContentText(messageBody)
.SetSmallIcon(Resource.Drawable.main)
.SetOngoing(true)
.Build();
StartForeground(SERVICE_RUNNING_NOTIFICATION_ID, notification);
//do you work
return StartCommandResult.Sticky;
}
void CreateNotificationChannel()
{
if (Build.VERSION.SdkInt < BuildVersionCodes.O)
{
// Notification channels are new in API 26 (and not a part of the
// support library). There is no need to create a notification
// channel on older versions of Android.
return;
}
var channelName = Resources.GetString(Resource.String.channel_name);
var channelDescription = GetString(Resource.String.channel_description);
var channel = new NotificationChannel("10111", channelName, NotificationImportance.Default)
{
Description = channelDescription
};
var notificationManager = (NotificationManager)GetSystemService(NotificationService);
notificationManager.CreateNotificationChannel(channel);
}
}
}
Here is a similar thread about your needs.
How to create service doing work at period time in Xamarin.Forms?
For IOS background Tasks. you can refer to this thread