Add a label on MGLPolygon - ios

Question

I have a situation where I need to draw an MGLPolygon on a map(MapBox) and I also want to give a UILabel like text on the polygon. The label has to be at the centroid of the polygon and it should be always visible. I found a code with which I can find the centroid of a given polygon, But I couldn't add a label to polygon. I have done the coding in SWIFT so swift developers please help me. Thanks in advance and Happy Coding :)

Answer 1

func mapView(_ mapView: MGLMapView, viewFor annotation: MGLAnnotation) -> MGLAnnotationView? {
if let currentAnnotation = annotation as? AreaAnnotation {
let reuseIdentifier = currentAnnotation.areaTitle
var annotationView = mapView.dequeueReusableAnnotationView(withIdentifier: reuseIdentifier!)
if annotationView == nil {
annotationView = MGLAnnotationView(reuseIdentifier: reuseIdentifier)
annotationView?.frame = CGRect(x: 0, y: 0, width: 120, height: 90)
annotationView!.backgroundColor = UIColor.clear
let detailsLabel:UILabel = UILabel()
detailsLabel.frame = CGRect(x: 30, y: 60, width: 60, height: 25)
detailsLabel.textAlignment = .center
detailsLabel.text = currentAnnotation.areaTitle
// detailsLabel.textColor = UIColor(red:175/255 ,green:255/255, blue:255/255 , alpha:0.75)
detailsLabel.textColor = UIColor.white
detailsLabel.font = UIFont(name: "HelveticaNeue-CondensedBlack", size: 15)
let strokeTextAttributes = [NSAttributedStringKey.strokeColor : UIColor.black, NSAttributedStringKey.strokeWidth : -5.0,] as [NSAttributedStringKey : Any]
detailsLabel.attributedText = NSAttributedString(string: titleLabel.text!, attributes: strokeTextAttributes)
detailsLabel.backgroundColor = UIColor.black.withAlphaComponent(1.0)
detailsLabel.clipsToBounds = true
detailsLabel.layer.cornerRadius = 5.0
detailsLabel.layer.borderWidth = 2.0
detailsLabel.layer.borderColor = UIColor.white.cgColor
annotationView?.addSubview(detailsLabel)
}
return annotationView
}
return nil
}
Thanks #jmkiley but I wanted to clear out that issue as fast as possible so I used this tweak, which was the exact thing I wanted.

Answer 2

If you have the center point of the polygon, you could use it to create a MGLPointFeature. Then create a MGLShapeSource and MGLSymbolStyleLayer with it. Provide the text to that layer. For example:
import Mapbox
class ViewController: UIViewController, MGLMapViewDelegate {
var mapView : MGLMapView!
var line: MGLPolyline?
override func viewDidLoad() {
super.viewDidLoad()
mapView = MGLMapView(frame: view.bounds)
view.addSubview(mapView)
mapView.delegate = self
let coords = [
CLLocationCoordinate2D(latitude: 38.0654, longitude: -88.8135),
CLLocationCoordinate2D(latitude: 41.7549, longitude: -88.8135),
CLLocationCoordinate2D(latitude: 41.7549, longitude: -83.1226),
CLLocationCoordinate2D(latitude: 38.0654, longitude: -83.1226)
]
let polygon = MGLPolygon(coordinates: coords, count: UInt(coords.count))
mapView.addAnnotation(polygon)
}
func mapView(_ mapView: MGLMapView, didFinishLoading style: MGLStyle) {
let point = MGLPointFeature()
point.coordinate = CLLocationCoordinate2D(latitude: 40.0781, longitude: -85.6714)
let source = MGLShapeSource(identifier: "point-source", features: [point], options: nil)
style.addSource(source)
let layer = MGLSymbolStyleLayer(identifier: "point-layer", source: source)
layer.text = MGLStyleValue(rawValue: "Polygon A")
style.addLayer(layer)
}
}