无法获取iOS MapKit Annotation来显示标题和副标题

Question

I'm having issues showing a map annotation within xCode. I am able to show a pin on the correct coordinates, however I cannot seem to figure out how to show an annotation with a title and subtitle.

I'm a newbie to xCode and Swift, so apologies if I use incorrect terminology (or if this is a really simple problem to solve!) I've been searching the web for about 2 hours now, trying different variations to my code, but I can't get it working!

I'm developing a simple app where users can browse locations and then see it pinned on a map. Once people click through from a location to the MapViewController, I'm trying to just show a map with the location pinned and an annotation with title and subtitle. I've figured everything out except for the title and subtitle, so I'd appreciate any help!

override func viewDidLoad() {
    super.viewDidLoad()

    // Location pin
    let initialLocation = CLLocation(latitude: location.latitude, longitude: location.longitude)
    self.centerMapOnLocation(location: initialLocation)


    // Annotation
    let annotation = MKPointAnnotation()
    annotation.title = self.location.name
    annotation.subtitle = self.location.type
    annotation.coordinate = CLLocationCoordinate2D(latitude: location.latitude, longitude: location.longitude)
    mapView.addAnnotation(location)

}

// Map Center on Location
func centerMapOnLocation(location: CLLocation) {
    let regionRadius: CLLocationDistance = 1000
    let coordinateRegion = MKCoordinateRegionMakeWithDistance(location.coordinate,
    regionRadius * 2.0, regionRadius * 2.0)
    mapView.setRegion(coordinateRegion, animated: true)
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
}

Answer 1

Make sure your class conforms to the MGLMapViewDelegate and use the following method.

func mapView(_ mapView: MGLMapView, annotationCanShowCallout annotation: MGLAnnotation) -> Bool {
   return true
}

Answer 2

I wonder if you should add annotation instead of location into the mapView, ie:

mapView.addAnnotation(annotation)

And if you want to show the callout programmatically, you can call like this:

mapView.selectAnnotation(annotation, animated: true)