How to change displayPriority of MKUserLocation annotation in MapView? - ios

Question

I have a MapView displaying some annotations with displayPriority = .defaultHight to allow automatic clustering.
The MapView also displays the current user location which has a default display priority of required.
This causes my annotations to be hidden by the user location annotation when they are very close together.
I want to change this behavior by setting the display priority of the user location annotation to defaultLow.
I tried using this approach:
func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
if annotation is MKUserLocation {
let userView = mapView.view(for: annotation)
userView?.displayPriority = .defaultLow
return userView
}
return mapView.view(for: annotation)
}
However userView is always nil and therefore my displayPriority modification is not applied.
Any ideas how the displayPriority of the MKUserLocation annotation view can be changed?

Answer 1

I spent hours trying to solve this problem by customizing the default user location annotation, but to no avail.
Instead, as a workaround, I made my own location marker and hid the default location annotation. Here's my code:
Add an annotaion variable to your viewController:
private var userLocation: MKPointAnnotation?
In your viewDidLoad, hide the default location marker:
mapView.showsUserLocation = false
Update the location in didUpdateLocations:
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
guard let userLocation = locations.first else { return }
if self.userLocation == nil {
let location = MKPointAnnotation()
location.title = "My Location"
location.coordinate = userLocation.coordinate
mapView.addAnnotation(location)
self.userLocation = location
} else {
self.userLocation?.coordinate = userLocation.coordinate
}
}
Then customize the annotation view in viewFor annotation:
func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
// user location annotation
let identifier = "userLocation"
var annotationView = mapView.dequeueReusableAnnotationView(withIdentifier: identifier)
if annotationView == nil {
annotationView = MKMarkerAnnotationView(annotation: annotation, reuseIdentifier: identifier)
(annotationView as? MKMarkerAnnotationView)?.markerTintColor = .blue
annotationView?.canShowCallout = true
} else {
annotationView?.annotation = annotation
}
annotationView?.displayPriority = .defaultLow
return annotationView
}
I changed the annotation's displayPriority to .defaultLow to make sure it won't hide other annotations.
Let me know if this helps!

Answer 2

In case anyone is still struggling with this, you can do this using func mapView(_ mapView: MKMapView, didAdd views: [MKAnnotationView]):
// MARK: - MKMapViewDelegate
func mapView(_ mapView: MKMapView, didAdd views: [MKAnnotationView]) {
for view in views {
if view.annotation is MKUserLocation {
view.displayPriority = .defaultLow
break
}
}
}
This way you can still use the system provided view for MKUserLocation without having to construct your own manually.