Background service confusion - xamarin

Question

I'm trying to find out how to keep an Android service running after the starting app is closed. I've tried looking at samples for background services (e.g this one, and some on the Xamarin site) but in every case the service stops running if the minimised app is 'swiped' off the screen. I don't want the service to accidently stop like this, it should run continually until a confirmed stop is requested. The service does not consume much in the way of resources, just gets a GPS location and posts it to a website every 2 minutes.
By way of background, I am a newbie to Xamarin/Android, but have in the past created several successful services in Windows with C#
(Later)
One sample I tried did leave an item in the Settings list of running apps, but didn't actually perform any service tasks once swiped off the screen. Additionally there was no icon in the status bar. After doing some reading it seems that my androidmanifest file is missing a 'service' attribute (although none of the samples I tried have this); what I have now tried is this
<service
android:name=".LocationService"
android:icon="#drawable/icon"
android:label="#string/service_name"
>
<intent-filter>
<action android:name="android.service.LocationService" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</service>
...but still no luck.

Answer 1

Have you had a look at the Xamarin sample here the source is here
They create a service like so:
[Service]
public class SimpleService : Service
{
System.Threading.Timer _timer;
public override StartCommandResult OnStartCommand (Android.Content.Intent intent, StartCommandFlags flags, int startId)
{
Log.Debug ("SimpleService", "SimpleService started");
DoStuff ();
return StartCommandResult.Sticky;
}
public override void OnDestroy ()
{
base.OnDestroy ();
_timer.Dispose ();
Log.Debug ("SimpleService", "SimpleService stopped");
}
public void DoStuff ()
{
_timer = new System.Threading.Timer ((o) => {
Log.Debug ("SimpleService", "hello from simple service");}
, null, 0, 4000);
}
public override Android.OS.IBinder OnBind (Android.Content.Intent intent)
{
throw new NotImplementedException ();
}
}
And start and stop it with this:
StartService (new Intent (this, typeof(SimpleService)));
StopService (new Intent (this, typeof(SimpleService)));
Also it sounds like you want a Sticky service Docs
When the system is under memory pressure, Android may stop any running services. The exceptions to this rule are services explicitly started in the foreground, which are discussed later in this article.
When a service is stopped by the system, Android will use the value returned from OnStartCommand to determine how or if the service should be restarted. This value is of type StartCommandResult, which can be any of the following:
Sticky – A sticky service will be restarted, and a null intent will be delivered to OnStartCommand at restart. Used when the service is continuously performing a long-running operation, such as updating a stock feed.
RedeliverIntent – The service is restarted, and the last intent that was delivered to OnStartCommand before the service was stopped by the system is redelivered. Used to continue a long-running command, such as the completion of a large file upload.
NotSticky – The service is not automatically restarted.
StickyCompatibility – Restart will behave like Sticky on API level 5 or greater, but will downgrade to pre-level 5 behavior on earlier versions.
Hope this helps.

Answer 2

Solved it now. The confusion was mainly due to many samples being out-of-date (using deprecated methods) and different suggestions for 'pure' Android projects and Xamarin ones. Certainly don't need to modify the androidmanifest file as I suggested above.
If anyone is trying to find something similar, my project is here.
Solving the initial issue has now raised some new questions, of course, but I will post separately about that if needed.