CODEWITHSUNDEEP
iosswiftmkmapview
DommyP
DommyP

Reputation: 14

mapView.addAnnotation() Not Adding Pins to Map until touching map

I have a mapView from storyboard and everything works, except for one thing: the annotations I make from a RESTful call and add to the map mapView.addAnnotation() don't show up on the map until I touch and move the map. Here's the relevant code:

class ViewController: UIViewController, MKMapViewDelegate {
    @IBOutlet weak var mapView: MKMapView!

    override func viewDidLoad() {
       super.viewDidLoad()
       self.mapView.delegate = self

       // API Call
       URLSession.shared.dataTask(with: mRequest) {
       (data, response, error) in do {

           let data = data

       ...

          let annotation = MKPointAnnotation()
          annotation.coordinate = CLLocationCoordinate2DMake(lat!, lon!)
          annotation.title = name as? String
          annotation.subtitle = details as? String
          self.mapView.addAnnotation(annotation)

       }
       ...
       }.resume()

    }
  }

Upvotes: 0

Views: 246

Answers (1)

Chris Allwein
Chris Allwein

Reputation: 2578

The issue is that you're updating the UI from a background thread. The block where you are adding the annotations is occurring as a result of the dataTask completing, and this is happening in the background. Wrap you annotation code in a DispatchQueue.main.async { } block and you should see the annotations show up fine.

DispatchQueue.main.async{
      let annotation = MKPointAnnotation()
      annotation.coordinate = CLLocationCoordinate2DMake(lat!, lon!)
      annotation.title = name as? String
      annotation.subtitle = details as? String
      self.mapView.addAnnotation(annotation)
}

Upvotes: 1

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