MKAnnotation Swift

Question

I am unsure how to annotate a map in the swift language. I don't know how to create the NSObject class. The following is code I tried but was unable to run:

import Foundation
import MapKit
class MapPin : MKAnnotation
{
    var mycoordinate: CLLocationCoordinate2D
    var mytitle: String
    var mysubtitle: String

    func initMapPin (coordinate: CLLocationCoordinate2D!, title: String!, subtitle: String!)
    {
        mycoordinate = coordinate
        mytitle = title
        mysubtitle = subtitle
    }
}

Answer 1

1. All initialization methods in Swift must simply be "init"
2. MKAnnotation requires that the object inherit from NSObjectProtocol. To do that, you should have your class inherit from NSObject
3. You should declare your properties to match those of the MKAnnotation protocol
4. You should not declare your parameters as Implicitly Unwrapped Optionals unless you really have to. Let the compiler check if something is nil instead of throwing runtime errors.

This gives you the result:

class MapPin : NSObject, MKAnnotation {
    var coordinate: CLLocationCoordinate2D
    var title: String?
    var subtitle: String?

    init(coordinate: CLLocationCoordinate2D, title: String, subtitle: String) {
        self.coordinate = coordinate
        self.title = title
        self.subtitle = subtitle
    }
}