CODEWITHSUNDEEP
c#iosgoogle-mapsxamarin.iosxamarin
gpopoteur
gpopoteur

Reputation: 1519

Xamarin iOS Google Maps SDK - Exception with mapView.AddObserver()

I'm trying to get the current position of the device using Google Maps SDK in Xamarin.iOS, I got the following code but I'm getting an exception.

I've imported the Google Maps SDK for iOS in Xamarin

using Google.Maps;

This is my code:

MapView gmapView;
public override void ViewDidLoad ()
{
    base.ViewDidLoad ();

    CameraPosition camera = CameraPosition.FromCamera (latitude: 40.7056308, 
            longitude: -73.9780035, 
            zoom: 13);
    mapView = MapView.FromCamera (new RectangleF(0, 0, View.Frame.Width, View.Frame.Bottom - 50), camera);
    mapView.Settings.CompassButton = true;
    mapView.Settings.MyLocationButton = true;

    // Listen to the myLocation property of GMSMapView.
    mapView.AddObserver (this, new NSString ("myLocation"), NSKeyValueObservingOptions.New, IntPtr.Zero);

    // More code ...
    // ...

    // Ask for My Location data after the map has already been added to the UI.
    InvokeOnMainThread (()=> mapView.MyLocationEnabled = true);
}

Then I define the method that should be called when the position of the user changes:

public override void ObserveValue (NSString keyPath, NSObject ofObject, NSDictionary change, IntPtr context)
{
    if (!firstLocationUpdate) {
        // If the first location update has not yet been recieved, then jump to that
        // location.
        firstLocationUpdate = true; 
        var location = change.ObjectForKey (NSValue.ChangeNewKey) as CLLocation;
        mapView.Camera = CameraPosition.FromCamera (location.Coordinate, 14);
    }
}

But I'm getting the following exception and have been stuck with this for a while with no luck :/

MonoTouch.Foundation.MonoTouchException: Objective-C exception thrown.  Name: NSInternalInconsistencyException Reason: <MapViewController: 0x1b6648c0>: An -   observeValueForKeyPath:ofObject:change:context: message was received but not handled.

Upvotes: 0

Views: 1492

Answers (2)

tomec
tomec

Reputation: 52

I've run into the same problem, was trying everything but nothing helped. Mayber there is some bug in Xamarin's Google Maps library.

Finally I've rewritten the observer to timer. It's ugly but it's working for now.

NSRunLoop.Main.AddTimer (NSTimer.CreateRepeatingTimer (0.2d, (timer) => {
    var location = mapView.MyLocation;

    if (location == null) {
        return;
    } else {
        timer.Invalidate ();
    }

    //do what you need with current location

}), NSRunLoopMode.Default);

Upvotes: 0

Luca
Luca

Reputation: 770

Try to move this line

mapView.AddObserver (this, new NSString ("myLocation"), NSKeyValueObservingOptions.New, IntPtr.Zero);

Inside the InvokeOnMainThread, like this:

InvokeOnMainThread (()=> { 
    mapView.MyLocationEnabled = true;
    mapView.AddObserver (this, new NSString ("myLocation"), NSKeyValueObservingOptions.New, IntPtr.Zero);
});`

Upvotes: 1

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