MKOverlayRenderer stretches image - ios

Question

I would like to place an image in a map overlay which will scale along with the map. Using the code below, the image appears in the map view but it is stretched to fit the view. How can I keep the original aspect ratio of the image inside the overlay?
MapOverlay.swift
import UIKit
import MapKit
class MapOverlay: NSObject, MKOverlay {
var coordinate: CLLocationCoordinate2D
var boundingMapRect: MKMapRect
init(coord: CLLocationCoordinate2D, rect: MKMapRect) {
self.coordinate = coord
self.boundingMapRect = rect
}
}
MapOverlayView.swift
import UIKit
import MapKit
class MapOverlayView: MKOverlayRenderer {
var overlayImage: UIImage
init(overlay: MKOverlay, overlayImage:UIImage) {
self.overlayImage = overlayImage
super.init(overlay: overlay)
}
override func draw(_ mapRect: MKMapRect, zoomScale: MKZoomScale, in context: CGContext) {
let mapImage = overlayImage.cgImage
let mapRect = rect(for: overlay.boundingMapRect)
context.scaleBy(x: 1.0, y: -1.0)
context.translateBy(x: 0.0, y: -mapRect.size.height)
context.draw(mapImage!, in: mapRect)
}
}
ViewController.swift
import UIKit
import MapKit
class ViewController: UIViewController {
#IBOutlet weak var mapview: MKMapView!
override func viewDidLoad() {
super.viewDidLoad()
mapview.delegate = self
let location = CLLocationCoordinate2D(latitude: 47.6062, longitude: -122.3320)
let span = MKCoordinateSpanMake(2.0, 2.0)
let region = MKCoordinateRegion(center: location, span: span)
mapview.setRegion(region, animated: true)
let rec = mapview.visibleMapRect
let overlay = MapOverlay(coord: location, rect: rec)
mapview.add(overlay)
}
}
extension ViewController: MKMapViewDelegate {
func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
if overlay is MapOverlay {
let logo = UIImage(named: "swift")
let overlayView = MapOverlayView(overlay: overlay, overlayImage: logo)
return overlayView
} else {
return MKPolylineRenderer()
}
}
}

Answer 1

In your ViewController.swift, in viewDidLoad(),
let rec = mapview.visibleMapRect
Change this, rec should be exactly same size of the image used.
let location = //Give your location here in CLLocationCoordinate2D
//1. Show direction Using Overlays
let span = MKCoordinateSpanMake(1.0, 1.0)
let region = MKCoordinateRegion(center: location, span: span)
let mapRect: MKMapRect = helperClass.MKMapRectForCoordinateRegion(region: region)
let overlay = MapOverlay(identifier: title, coord: location, rect: mapRect)
mapView.add(overlay)
The function to get MKMapRect
func MKMapRectForCoordinateRegion(region:MKCoordinateRegion) -> MKMapRect {
let topLeft = CLLocationCoordinate2D(latitude: region.center.latitude + (region.span.latitudeDelta/2), longitude: region.center.longitude - (region.span.longitudeDelta/2))
let bottomRight = CLLocationCoordinate2D(latitude: region.center.latitude - (region.span.latitudeDelta/2), longitude: region.center.longitude + (region.span.longitudeDelta/2))
let a = MKMapPointForCoordinate(topLeft)
let b = MKMapPointForCoordinate(bottomRight)
return MKMapRect(origin: MKMapPoint(x:min(a.x,b.x), y:min(a.y,b.y)), size: MKMapSize(width: abs(a.x-b.x), height: abs(a.y-b.y)))
}
The sample project can be found in this link