MapKit Annotations Disappearing

Question

I have an array of latitudes and another array of longitudes that I add to an array of type CLLocationCoordinate2D. I then use the new array to annotate multiple points on t

Answer 1

I was experiencing a similar issue. My best guess is that it has something to do with how iOS 11 detects pin collisions. Implementing a custom annotation view or reverting to use the iOS 10 pin fixed the problem for me.

For example, implementing the following should fix your code:

class MultiMapVC: UIViewController, MKMapViewDelegate, CLLocationManagerDelegate {
   override func viewDidLoad() {
       super.viewDidLoad()
       mapView.delegate = self    
    }

    func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
       guard let annotation = annotation as? MKPointAnnotation else { return nil }

       let identifier = "pin-marker"
       var view: MKAnnotationView

       if let dequeuedView = mapView.dequeueReusableAnnotationView(withIdentifier: identifier) as? MKPinAnnotationView {
           dequeuedView.annotation = annotation
           view = dequeuedView
       } else {
           view = MKPinAnnotationView(annotation: annotation, reuseIdentifier: identifier)
       }
       return view
   }
}

If this doesn't work, there is a displayPriority property that is worth looking into as it is responsible for helping to determine when pins should be hidden/shown at different zoom levels. More info at https://developer.apple.com/documentation/mapkit/mkannotationview/2867298-displaypriority

Hope this helps.