class extension not being called - unable to configure annotations on map - swift

Question

I'm on Swift 5 and Xcode 11, currently trying to create a map with predefined annotations using custom images instead of the default markers. I've been playing around with Apple's sample code for AnnotatingMapWithCustomData and could tailor it to what I needed. But once I tried to copy the code into my own project, the annotations showed up as default markers instead of the custom annotationViews I configured.
import UIKit
import MapKit
class MapViewController: UIViewController {
#IBOutlet private weak var mapView: MKMapView!
private var allAnnotations: [MKAnnotation]?
private var displayedAnnotations: [MKAnnotation]? {
willSet {
if let currentAnnotations = displayedAnnotations {
mapView.removeAnnotations(currentAnnotations)
}
}
didSet {
if let newAnnotations = displayedAnnotations {
mapView.addAnnotations(newAnnotations)
}
}
}
override func viewDidLoad() {
super.viewDidLoad()
registerMapAnnotationViews()
// Create the array of annotations and the specific annotations for the points of interest.
allAnnotations = [ShrekAnnotation(), CoffeeAnnotation()]
// Dispaly all annotations on the map.
displayedAnnotations = allAnnotations
centerMapOnLondon()
}
/// - Tag: RegisterAnnotationViews
private func registerMapAnnotationViews() {
mapView.register(MKAnnotationView.self, forAnnotationViewWithReuseIdentifier: NSStringFromClass(ShrekAnnotation.self))
mapView.register(MKAnnotationView.self, forAnnotationViewWithReuseIdentifier: NSStringFromClass(CoffeeAnnotation.self))
}
private func centerMapOnLondon() {
let span = MKCoordinateSpan(latitudeDelta: 0.05, longitudeDelta: 0.05)
let center = CLLocationCoordinate2D(latitude: 51.507911, longitude: -0.132222)
mapView.setRegion(MKCoordinateRegion(center: center, span: span), animated: true)
}
}
extension MapViewController: MKMapViewDelegate {
/// - Tag: CreateAnnotationViews
func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
guard !annotation.isKind(of: MKUserLocation.self) else {
// Make a fast exit if the annotation is the `MKUserLocation`, as it's not an annotation view we wish to customize.
return nil
}
var annotationView: MKAnnotationView?
if let annotation = annotation as? ShrekAnnotation {
annotationView = setupShrekAnnotationView(for: annotation, on: mapView)
} else if let annotation = annotation as? CoffeeAnnotation {
annotationView = setupCoffeeAnnotationView(for: annotation, on: mapView)
}
return annotationView
}
/// - Tag: ConfigureAnnotationViews
private func setupShrekAnnotationView(for annotation: ShrekAnnotation, on mapView: MKMapView) -> MKAnnotationView {
let reuseIdentifier = NSStringFromClass(ShrekAnnotation.self)
let view = mapView.dequeueReusableAnnotationView(withIdentifier: reuseIdentifier, for: annotation)
view.canShowCallout = true
// Provide the annotation view's image.
let image = #imageLiteral(resourceName: "map-shrek1")
view.image = image
return view
}
/// - Tag: ConfigureAnnotationViews
private func setupCoffeeAnnotationView(for annotation: CoffeeAnnotation, on mapView: MKMapView) -> MKAnnotationView {
let reuseIdentifier = NSStringFromClass(CoffeeAnnotation.self)
let view = mapView.dequeueReusableAnnotationView(withIdentifier: reuseIdentifier, for: annotation)
view.canShowCallout = true
// Provide the annotation view's image.
let image = #imageLiteral(resourceName: "map-cof1")
view.image = image
return view
}
}
Apparently the class extension is not being called but I don't know how to fix this. The code that worked before I tried implementing it in my own project is identical. Could I have missed something I should've copied too or can you find the reason for the bug in the code?
Thanks for any help.

Answer 1

I think you are not setting the mapView delegate hence viewFor annotation is not being triggered and your custom annotation view is not appearing on map. Set
mapView.delegate = self
override func viewDidLoad() {
super.viewDidLoad()
mapView.delegate = self
registerMapAnnotationViews()
// Create the array of annotations and the specific annotations for the points of interest.
allAnnotations = [ShrekAnnotation(), CoffeeAnnotation()]
// Dispaly all annotations on the map.
displayedAnnotations = allAnnotations
centerMapOnLondon()
}
Hope this helps