Swift display annotations in mapView in another thread - ios

Question

This code does not add annotations to mapView. I saw in one answer that mapView function is called every time addAnotation is called so where's the problem? But when I move map they show up.
func addPlacesMarkers(location:CLLocation) {
self.communication.getJsonData(self.getPubsNearByCreator(location)) { (finalData, error) -> Void in
if error != nil {
print(error)
} else {
if let row: NSArray = finalData {
for var i = 0; i < row.count; i++ {
let lat = row[i]["lat"] as! String
let lng = row[i]["lng"] as! String
let title = row[i]["name"] as! String
let id = row[i]["id"] as! String
let point = CustomizedAnotation(id: Int(id)!, name: title)
point.title = title
point.coordinate.latitude = Double(lat)!
point.coordinate.longitude = Double(lng)!
let keyExists = self.places[Int(id)!] != nil
if keyExists == false {
self.places.updateValue(point, forKey: Int(id)!)
}
}
var finalPlaces :[MKPointAnnotation] = []
for place in self.places.values {
finalPlaces.append(place)
}
self.mView.addAnnotations(finalPlaces)
self.mView.showsPointsOfInterest = false
}
}
}
}

Answer 1

You can't modify the UI in a thread different from the main.
You should put your UI modification code inside a dispatch_async block like this:
dispatch_async(dispatch_get_main_queue()) {
//Your code that modify the UI
self.mView.addAnnotations(finalPlaces)
}