Mapbox iOS - Custom annotations are invisible - ios

Question

I'm trying to create simple custom map annotations on Mapbox iOS (5.5.0) by implementing MGLMapViewDelegate protocol. Annotations are actually added to the map, but they are invisible. I can predict its coordinate and open its callout, so, I know it's there.
I have even tried copying the exact codes given on Mapbox examples to get the same result. Can it be a lack of some framework elements?
My code:
class MainViewController: UIViewController, MGLMapViewDelegate {
override func viewDidLoad() {
super.viewDidLoad()
// Set the map’s size, style, center coordinate, zoom level, and tint color.
let mapView = MGLMapView(frame: view.bounds)
let coordinates = CLLocationCoordinate2D(latitude: 40.4561, longitude: 49.7263)
mapView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
mapView.styleURL = MGLStyle.darkStyleURL(withVersion: 9)
mapView.setCenter(coordinates, zoomLevel: 15, animated: false)
//mapView.userTrackingMode = .followWithHeading
//mapView.showsUserHeadingIndicator = true
view.addSubview(mapView)
mapView.delegate = self
let marker = MGLPointAnnotation()
marker.coordinate = coordinates
marker.title = "Area 51"
marker.subtitle = "There is no way in!"
mapView.addAnnotation(marker)
}
// Use the default marker. See also: our view annotation or custom marker examples.
func mapView(_ mapView: MGLMapView, viewFor annotation: MGLAnnotation) -> MGLAnnotationView? {
guard annotation is MGLPointAnnotation else {
return nil
}
let annotationAvailable = isAnnotationAvailable(annotation)
let reuseIdentifier = "\(annotationAvailable)"
var annotationView = mapView.dequeueReusableAnnotationView(withIdentifier: reuseIdentifier)
if (annotationView == nil) {
annotationView = MGLAnnotationView()
annotationView = CustomAnnotationView(reuseIdentifier: reuseIdentifier)
annotationView!.bounds = CGRect(x: 0, y: 0, width: 40, height: 40)
if (!annotationAvailable) {
annotationView!.backgroundColor = UIColor(displayP3Red: 255, green: 0, blue: 0, alpha: 1)
}
else {
annotationView!.backgroundColor = UIColor(displayP3Red: 0, green: 255, blue: 0, alpha: 1)
}
}
return annotationView
}
// Allow callout view to appear when an annotation is tapped.
func mapView(_ mapView: MGLMapView, annotationCanShowCallout annotation: MGLAnnotation) -> Bool {
return true
}
func isAnnotationAvailable(_ annotation: MGLAnnotation) -> Bool {
return false
}
}
class CustomAnnotationView: MGLAnnotationView {
override func layoutSubviews() {
super.layoutSubviews()
// Use CALayer’s corner radius to turn this view into a circle.
layer.cornerRadius = bounds.width / 2
layer.borderWidth = 2
layer.borderColor = UIColor.white.cgColor
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
// Animate the border width in/out, creating an iris effect.
let animation = CABasicAnimation(keyPath: "borderWidth")
animation.duration = 0.1
layer.borderWidth = selected ? bounds.width / 4 : 2
layer.add(animation, forKey: "borderWidth")
}
}
The result:
Mapbox Screenshot