Xamarin.iOS custom Mapdelegate

Question

In my Xamarin.iOS project i have my own delegate class as subclass of MKMapViewDelegate

In the ViewController I set my delegate as delegate of the MapView.

public override async void ViewDidLoad()
    {
        base.ViewDidLoad();
        mapView.delegate = new MyMapDelegate(this);
    }

Now in my delegate class i add a Button for each Pin. This button draws an overlay to the map. Here I have to set mapview.delegate = null, otherwise the App Crashes.

But if I set mapView.delegate = null the App doesnt make use of the "DequeueReusableAnnotation" method and of course the Application won't make use of DidUpdateUserLocation anymore.

The Error i get if I don't set mapviews delegate to null :

System.InvalidOperationException: Event registration is overwriting existing delegate. Either just use events or your own delegate: testApp.iOS.MyMapDelegate MapKit.MKMapView+_MKMapViewDelegate

So how can i set a Delegate in Xamarin?

EDIT

class MyMapDelegate: MKMapViewDelegate
    {
        ... some vars

        public MyMapDelegate(MapController mapController)
        {
            this.mapController = mapController;
        }
        public override MKAnnotationView GetViewForAnnotation(MKMapView mapView, IMKAnnotation annotation)
        {
            //everything works fine here for AnnotationView
            myBtn += (sender,e) => {
              //mapView.Delegate = null;
                userLocation = mapView.UserLocation.Coordinate 
                ...
                mapView.OverlayRenderer = (mv,ol) => myLine;
                mapView.AddOverlay(myWay.polyLine,MKOverlayLevel.AboveRoads)
            };
        }

My Guess is maybe the Error appears cause i call methods from mapView like OverlayRenderer and Userlocation?

Answer 1

instead of calling:

mapview.OverlayRenderer = (mv,ol) => routeLine;

I had to override the method :

   public override MKOverlayRenderer OverlayRenderer(MKMapView mapView, IMKOverlay overlay)
        {
            var myPolyLine= new MKPolylineRenderer(myWay.Polyline)
            {
                LineWidth = 2.0f,
                StrokeColor = UIColor.Yellow
            };
            return myPolyLine;
        }