MKAnnotation just shown after move camera (swift)

Question

I am trying to use the MapKit-Framework in iOS. I have a map, where I draw a polyline. Now I want to add some simple annotations. I add them to the map, but they are not shown directly. I have to move the camera. After I move the camera or use the zoom, the annotations are visible. What I have to call to refresh the map to show the annotations directly?

var zugEndeAnnotation : MKPointAnnotation = MKPointAnnotation();
zugEndeAnnotation.coordinate = CLLocationCoordinate2D(latitude: zugEnde.coordinate.latitude , longitude: zugEnde.coordinate.longitude);
self.map.addAnnotation(zugEndeAnnotation);

best regards