func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
   if let temp = annotation as? MyAnnotation {
      var aView = mapView.dequeueReusableAnnotationView(withIdentifier: "Pins")
      if aView == nil {
         aView = MKAnnotationView(annotation: temp, reuseIdentifier: "Pins")
         aView?.image = UIImage(named: "iconmap")
         aView?.canShowCallout = true
      } else {
         aView?.annotation = annotation
      }
      return aView
   }
   return nil
}