iOS Mapkit Annotation Pin Shrinking

Question

MapView is pin skrinking everytime. I'm using MKAnnotationView. Can anyone tell what what am I missing here why the pin shrinking? I want to show the pin like that star icon which is also annotation.

Also everytime I change the current location co-cordinate it will create new pin and old one also be there.

class CustomPointAnnotation: MKPointAnnotation {
  var imageName: String!
}

    func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
   
    if annotation is MKUserLocation {
           return nil
    }
    
     let annotationView = MKMarkerAnnotationView(annotation: annotation, reuseIdentifier: "MyMarker")
     annotationView.canShowCallout = true

     switch annotation.title! {
         case "Your Current Location":
             annotationView.glyphImage = UIImage(named: "user_location")
         default:
         annotationView.canShowCallout = true
         annotationView.glyphImage = UIImage(named: "user_location")
         let buttonPin = UIButton(type: .custom)
         buttonPin.frame = CGRect(x: 0, y: 0, width: 40, height: 40)
         buttonPin.setImage(UIImage(named: "PhoneIcon"), for: .normal)
         annotationView.rightCalloutAccessoryView = buttonPin
         annotationView.markerTintColor = UIColor.purple
     }
     return annotationView
 }

  func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    
    mapView.removeAnnotation(annotation)
    
    let currentLocationValue = manager.location!.coordinate
    let servicelocValue: CLLocationCoordinate2D = CLLocationCoordinate2DMake(coordinates.latitude, coordinates.longitude)
   
    let annotation1 = CustomPointAnnotation()
    annotation1.title = "Your Current Location"
    annotation1.coordinate = currentLocationValue
    annotation1.imageName = "user_location.png"

    let annotation2 = CustomPointAnnotation()
    annotation2.title = service ?? ""
    annotation2.subtitle = location
    annotation2.coordinate = servicelocValue
    annotation2.imageName = "user_location.png"
    
    annotations.append(annotation1)
    annotations.append(annotation2)
    
    mapView.addAnnotations(annotations)
    
    mapView.cameraZoomRange = MKMapView.CameraZoomRange(minCenterCoordinateDistance: 50, maxCenterCoordinateDistance: 2000)
    mapView.selectAnnotation(annotation2, animated: false)
}

}