Xamarin iOS : Keep app running while screen is off - ios

Question

I'm facing the following issue. I have an app that request location in "always" mode that for some reason goes to sleep when the screen is off. It also asks for accelerometer data. All these are running inside a long running Task.
I thought that "location always" would keep the app to receive location data and thus maintains the app running.
The second problem is that the app should play a sound under certain circumstances while the screen is off, to notify the user to unlock it because he must interact with the app.
My info.plist contains the following:
<key>UIBackgroundModes</key>
<array>
<string>bluetooth-central</string>
<string>remote-notification</string>
<string>processing</string>
<string>location</string>
</array>
But AFAIK, it does not help achieve what I want.
Thanks for your help.

Answer 1

Below is an example of LocationService usage with background mode.
public class LocationManager
{
protected CLLocationManager locMgr;
public event EventHandler<LocationUpdatedEventArgs> LocationUpdated = delegate { };
public LocationManager()
{
this.locMgr = new CLLocationManager
{
// This mode is resistant to applications being killed in the background
PausesLocationUpdatesAutomatically = false
};
if (UIDevice.CurrentDevice.CheckSystemVersion(8, 0))
{
locMgr.RequestAlwaysAuthorization();
}
if (UIDevice.CurrentDevice.CheckSystemVersion(9, 0))
{
locMgr.AllowsBackgroundLocationUpdates = true;
}
}
public CLLocationManager LocMgr
{
get { return this.locMgr; }
}
public void StartLocationUpdates()
{
if (CLLocationManager.LocationServicesEnabled)
{
LocMgr.DesiredAccuracy = 1;
LocMgr.LocationsUpdated += (object sender, CLLocationsUpdatedEventArgs e) =>
{
LocationUpdated(this, new LocationUpdatedEventArgs(e.Locations[e.Locations.Length - 1]));
};
LocMgr.StartUpdatingLocation();
}
}
}
When an application monitors the location service in background mode, you can try local notification to post with a sound
// Trigger by position
#IBAction func locationInterval(_ sender: Any) {
let content = UNMutableNotificationContent()
content.title = "xx"
content.body = "xx"
let coordinate = CLLocationCoordinate2D(latitude: 31.29065118, longitude: 118.3623587)
let region = CLCircularRegion(center: coordinate, radius: 500, identifier: "center")
region.notifyOnEntry = true
region.notifyOnExit = false
let trigger = UNLocationNotificationTrigger(region: region, repeats: true)
let requestIdentifier = "com.abc.testUserNotifications"
let request = UNNotificationRequest(identifier: requestIdentifier, content: content, trigger: trigger)
UNUserNotificationCenter.current().add(request, withCompletionHandler: nil)
}
Hope it helps.