CODEWITHSUNDEEP
iosswift
Saneth Chandrasekara
Saneth Chandrasekara

Reputation: 471

Could not cast value of type 'MKMapView' to 'MKOverlay'

I created a library in Xcode8 with a method used to add a map to MapKitView and I import that library to a sample project and I called the method in the library then I get an error called "Could not cast value of type 'MKMapView' (0xdc7a48) to 'MKOverlay' (0xdcca0c). (lldb) "

the code in library

import Foundation
import MapKit
public class mapLib: NSObject{

    public  class func createMap(mapView: MKMapView) ->MKMapView{
        let mapView = mapView
        //custom map URL
        let template = "http://tile.openstreetmap.org/{z}/{x}/{y}.png"
        let overlay = MKTileOverlay(urlTemplate: template)
        overlay.canReplaceMapContent = true
        mapView.add(overlay, level: .aboveLabels)
        return mapView;
    }
}

the code used in the sample app

import UIKit
import MapKit
import mapLib
class ViewController: UIViewController {

    @IBOutlet weak var mapV: MKMapView!

    override func viewDidLoad() {
        super.viewDidLoad()

        let view = mapLib.createMap(mapView: mapV)
        mapV.add(view as! MKOverlay)  /////// Thread 1: signal SIGABRT
        // Do any additional setup after loading the view, typically from a nib.
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}

I have commented the error in sample app code

Upvotes: 1

Views: 382

Answers (1)

David Pasztor
David Pasztor

Reputation: 54775

MKOverlay is a protocol that MKMapView doesn't conform to by default, hence the error. Adding an MKMapView object to another MKMapView as an overlay simply cannot work, since MKMapView isn't just a simple overlay object.

If what you actually need is to add all overlays of one MKMapView to the other, you need to use below code:

let view = mapLib.createMap(mapView: mapV)
mapV.addOverlays(view.overlays)

Upvotes: 1

Related Questions