Drag Custom Annotation View - swift

Question

I have my CoreData custom Annotation class:
extension Annotation: MKAnnotation {
public var coordinate: CLLocationCoordinate2D {
let cllCoordinate = CLLocationCoordinate2D(latitude: self.latitude, longitude: self.longitude)
return cllCoordinate
}
public var title: String? {
return self.objectId
}
class func keyPathsForValuesAffectingCoordinate() -> Set<String> {
return Set<String>([ #keyPath(latitude), #keyPath(longitude) ])
}
#nonobjc public class func fetchRequest() -> NSFetchRequest<Annotation> {
return NSFetchRequest<Annotation>(entityName: "Annotation")
}
#NSManaged public var latitude: Double
#NSManaged public var longitude: Double
#NSManaged public var dateTime: Date
#NSManaged public var type: String
#NSManaged public var objectId: String?
}
combined with a fetchedResultsController adding and deleting annotations works fine. But now a want to drag an annotation to another position. But only with setting isDraggable to true is not all. I can’t find newer descriptions how this could be integrated.
Here my viewFor method:
func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
guard annotation is Annotation else { return nil }
let identifier = "Annotation"
var annotationView = mapView.dequeueReusableAnnotationView(withIdentifier: identifier)
if annotationView == nil {
annotationView = MKAnnotationView(annotation: annotation, reuseIdentifier: identifier)
annotationView?.isDraggable = true
annotationView?.canShowCallout = true
} else {
annotationView!.annotation = annotation
}
let customAnno = annotation as! Annotation
let image = UIImage(named: customAnno.type)
annotationView!.image = image
return annotationView
}
What else do i need? I want to press on the annotation, stay pressed and go to another position, then release the finger and the annotation stays there.

Answer 1

When it drags, it needs to change the coordinate of the underlying annotation. It can’t do that if it’s read-only. So, if you want to make it draggable, you must give the coordinate property a setter:
public var coordinate: CLLocationCoordinate2D {
get {
CLLocationCoordinate2D(latitude: latitude, longitude: longitude)
}
set {
latitude = newValue.latitude
longitude = newValue.longitude
}
}