Xamarin Forms does not wait for GeoLocation approval on iOS - ios

Question

I am have Xamarin Forms cross platform application for iOS, Android and UWP. I use the Xam.Plugin.Geolocator to get the location from each of the devices. My challenge with iOS is on the first launch of the app on a device. My code runs through and detects that IsGeolocationEnabled for the Plugin.Geolocator.Abstractions.IGeolocator object is false before the use is ever presented with the option to allow the application to use the device's location. This causes my app to inform the user that Location Services are not enabled for the application.
Basically I am hitting the line of code below before the use is ever asked about location services:
if (!App.gobj_RealGeoCoordinator.IsGeolocationEnabled)
ls_ErrorMessage = resourcestrings.GetValue("NoLocationServicesMessage");
On the other platforms, UWP at least, it seems that the app is paused while waiting for the user to respond to the request to use location services. Android just seems to automatically allow access to location if an app uses it.
Any idea how I can have the iOS detect if the request to use location services has been answered or not on the first run? Any suggestions would be greatly appreciated.
UPDATE(1):
I have all the correct items in my info.plist as seen below. I do eventually get the request to use the location just after my app has already checked IsGeolocationEnabled and decided the user has not enabled location services for the app.
UPDATE (2):
So I made a little progress using the following code.
try
{
while (!App.gobj_RealGeoCoordinator.IsGeolocationEnabled)
{
await Task.Delay(1000);
}
ViewModelObjects.AppSettings.CanAccessLocation = App.gobj_RealGeoCoordinator.IsGeolocationEnabled;
}
catch (Exception ex)
{
XXXXXXX
}
The challenge is that the plugin appears to provide me no way of knowing in the user has not responded to the location services dialog (i.e. IsGeolocationEnabled == false) versus the user said no to the location services dialog (also IsGeolocationEnabled == false). Any suggestions?

Answer 1

The way this type of permission request occurs on iOS is through an asynchronous dialog prompt, which is only shown if needed (and not until it is needed). Basically, you need to set up a callback from the CLLocation API. I have a helper class that I use for this purpose, which makes it even easier. Just call GetCurrentDeviceLocation() and pass it a callback function. The callback will only be invoked once the user has granted permission to the app, or if they previously granted permission:
public class GeoLocationService
{
readonly CLLocationManager _locationManager;
WeakReference<Action<Position>> _callback;
public GeoLocationService()
{
_locationManager = new CLLocationManager ();
_locationManager.AuthorizationChanged += AuthorizationChanged;
}
void AuthorizationChanged (object sender, CLAuthorizationChangedEventArgs e)
{
Action<Position> callback;
if (_callback == null || !_callback.TryGetTarget (out callback)) {
return;
}
if (IsAuthorized(e.Status)) {
var loc = _locationManager.Location;
var pos = new Position(loc.Coordinate.Latitude, loc.Coordinate.Longitude);
callback (pos);
}
}
static bool IsAuthorized(CLAuthorizationStatus status)
{
return
status == CLAuthorizationStatus.Authorized
|| status == CLAuthorizationStatus.AuthorizedAlways
|| status == CLAuthorizationStatus.AuthorizedWhenInUse;
}
public void GetCurrentDeviceLocation (Action<Position> callback)
{
_callback = new WeakReference<Action<Position>> (callback);
if (UIDevice.CurrentDevice.CheckSystemVersion (8, 0)) {
if (_locationManager.Location == null) {
_locationManager.RequestWhenInUseAuthorization ();
return;
}
}
AuthorizationChanged (null, new CLAuthorizationChangedEventArgs (CLAuthorizationStatus.Authorized));
}
}