如何在Mapview swift ios中设置自定义图像？

  mapview.delegate = self

    func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
guard !(annotation is MKUserLocation) else {
    return nil
}

 let annotationIdentifier = "Identifier"
 var annotationView: MKAnnotationView?
 if let dequeuedAnnotationView = mapView.dequeueReusableAnnotationView(withIdentifier: annotationIdentifier) {
    annotationView = dequeuedAnnotationView
    annotationView?.annotation = annotation
}
else {
    annotationView = MKAnnotationView(annotation: annotation, reuseIdentifier: annotationIdentifier)
    annotationView?.rightCalloutAccessoryView = UIButton(type: .detailDisclosure)
}

 if let annotationView = annotationView {

    annotationView.canShowCallout = true
    annotationView.image = UIImage(named: "yourImagename”)
}
  return annotationView
}