CODEWITHSUNDEEP
iosswiftmapkitmktileoverlay
jamryu
jamryu

Reputation: 698

Getting an error "Expected a MKTileOverlay but got (null)" when trying to add MKTileOverlay object to MKMapView

MKMapView class is added and assigned delegate:

let mapView: MKMapView = {

    let map = MKMapView()
    map.translatesAutoresizingMaskIntoConstraints = false
    return map
}()

override func viewDidLoad() {

self.view.addSubview(mapView)

    mapView.delegate = self

let center = mapView.centerCoordinate

    NSLayoutConstraint.activate([
        mapView.topAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.topAnchor, constant: 0),
        mapView.leftAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.leftAnchor, constant: 0),
        mapView.rightAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.rightAnchor, constant: 0),
        mapView.bottomAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.bottomAnchor, constant: 0)
    ])
}

Then the mapView is assigned center coordinate and span is set. zoomLevel is set to 1

let span = MKCoordinateSpan(latitudeDelta: 0, longitudeDelta: 360 / pow(2, Double(zoomLevel)) * Double(mapView.frame.size.width) / 256)
        setRegion(MKCoordinateRegion(center: coordinate, span: span), animated: animated)

// I wrote URL like this because I was told that MKTileOverlay class will take care of z, x, and y value.

let urlTemplate = "https://tile.openweathermap.org/map/temp_new/{z}/{x}/{y}.png?appid={my API ID}"

// urlTemplate is added to MKTileOverlay

            let overlay = MKTileOverlay(urlTemplate: urlTemplate)

            overlay.canReplaceMapContent = true

// And just when I am about to add overlay to mapView, the app will crash: 

self.mapView.addOverlay(overlay)

// It takes me to AppDelegate.swift and then it shows this message:

Thread 1: Exception: "Expected a MKTileOverlay but got (null)"

Everything was added to viewDidLoad().

I also added renderedFor delegate functions. Like this:

func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {

    var renderer = MKTileOverlayRenderer()

    print("overlay rendered For: \(overlay)")

    if overlay is MKTileOverlay {
        renderer = MKTileOverlayRenderer(overlay:overlay)
        renderer.alpha = 0.8
    }

    return renderer
}

Upvotes: 0

Views: 224

Answers (1)

Peter
Peter

Reputation: 29

I had the same problem and what was causing the crash for me was the initialisation of MKTileOverlayRenderer() without specifying an overlay.

So basically, your code inside the mapView(_:rendererFor:) delegate method should be:

func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {

    print("overlay rendered For: \(overlay)")

    if let overlay = overlay as? MKTileOverlay {
        renderer = MKTileOverlayRenderer(overlay: overlay)
        renderer.alpha = 0.8
        return renderer.alpha
    } else {
        return MKOverlayRenderer(overlay: overlay)
    }

}

Upvotes: 0

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