Passing Data over Segue From a mapView MKAnnotiation that has been tapped

Question

I am trying to pass data over a segue created by tapping an MkAnnotation callout using the calloutAccessoryControlTapped control. I want to go to the EventViewController and make a screen with more information about the MkAnnotation that was selected.

I've tried a number of difference methods including creating a custom class and trying to send that. The segue happens correctly but no data is passed to my second UIViewController (eventViewController).

I assume I am doing the wrong thing every time, but am finding it hard to debug the code due to the point at which I am assigning the data to the variable is also the trigger for the segue.

i.e. I am assuming the data isn't getting assigned at all, but the "selectedAnnotation" variable is getting passed across correctly but obviously its hard to tell.

    override func prepare(for segue: UIStoryboardSegue, sender: (Any)?) {
        if segue.identifier == "goToEventScreen" {
            selectedAnnotation = mapView.selectedAnnotations.lastObject as? MKAnnotation
            let destinationVC = segue.destination as! EventViewController
            destinationVC.points = selectedAnnotation
        }
    }
}
'''
extension ViewController: MKMapViewDelegate {
    func mapView(_ mapView: MKMapView, annotationView view: MKAnnotationView,
                 calloutAccessoryControlTapped control: UIControl){
        performSegue(withIdentifier: "goToEventScreen", sender: self)
    }
}

Thanks in advance.

Answer 1

You need to set your annotationView in the delegate method as the sender of performSegue method.

extension ViewController: MKMapViewDelegate {
    func mapView(_ mapView: MKMapView, annotationView view: MKAnnotationView, calloutAccessoryControlTapped control: UIControl) {
        performSegue(withIdentifier: "goToEventScreen", sender: view)
    }
}

Then in prepare for segue method:

override func prepare(for segue: UIStoryboardSegue, sender: (Any)?) {
    if segue.identifier == "goToEventScreen" {
        if let annotationView = sender as? MKAnnotationView {
            selectedAnnotation = annotationView.annotation
            let destinationVC = segue.destination as! EventViewController
            destinationVC.points = selectedAnnotation
        }
    }
}

What you do is getting the annotation from the selected annotationView and assigning it to the destinationVC's points.