Add Custom Image via a Subclass to Annotation and Add a Segue - ios

Question

I would like to add a custom image for a callout annotation via a subclass (previous questions did not include using a subclass)
Here is my code thus far:
Subclass named "Capital.swift"
import MapKit
import UIKit
class Capital: NSObject, MKAnnotation {
var title: String?
var coordinate: CLLocationCoordinate2D
var info: String
// here we would add the custom image
init(title: String, coordinate: CLLocationCoordinate2D, info: String) {
self.title = title
self.coordinate = coordinate
self.info = info
// add additional lines as needed
}
}
Here is my code for the ViewController.swift
import MapKit
import UIKit
class ViewController: UIViewController, MKMapViewDelegate {
#IBOutlet var mapView: MKMapView!
override func viewDidLoad() {
super.viewDidLoad()
let london = Capital(title: "London", coordinate: CLLocationCoordinate2D(latitude: 51.507222, longitude: -0.1275), info: "Home to the 2012 Summer Olympics.")
let oslo = Capital(title: "Oslo", coordinate: CLLocationCoordinate2D(latitude: 59.95, longitude: 10.75), info: "Founded over a thousand years ago.")
let paris = Capital(title: "Paris", coordinate: CLLocationCoordinate2D(latitude: 48.8567, longitude: 2.3508), info: "Often called the City of Light.")
let rome = Capital(title: "Rome", coordinate: CLLocationCoordinate2D(latitude: 41.9, longitude: 12.5), info: "Has a whole country inside it.")
let washington = Capital(title: "Washington DC", coordinate: CLLocationCoordinate2D(latitude: 38.895111, longitude: -77.036667), info: "Named after George himself.")
mapView.addAnnotations([london, oslo, paris, rome, washington])
}
func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
let identifier = "Capital"
if annotation is Capital {
if let annotationView = mapView.dequeueReusableAnnotationView(withIdentifier: identifier) {
annotationView.annotation = annotation
return annotationView
} else {
let annotationView = MKPinAnnotationView(annotation:annotation, reuseIdentifier:identifier)
annotationView.isEnabled = true
annotationView.canShowCallout = true
let btn = UIButton(type: .detailDisclosure)
annotationView.rightCalloutAccessoryView = btn
return annotationView
}
}
return nil
}
Here we add the custom image to the annotationView
func mapView(_ mapView: MKMapView, annotationView view: MKAnnotationView, calloutAccessoryControlTapped control: UIControl) {
let capital = view.annotation as! Capital
let placeName = capital.title
let placeInfo = capital.info
// Add custom image
// Add Segue
performSegue(withIdentifier: "segue1", sender: (capital.title, capital.coordinate, capital.info))
}
}
Thanks