Restrict map panning to an area

import Mapbox
 
class ViewController: UIViewController, MGLMapViewDelegate {
 
private var colorado: MGLCoordinateBounds!
 
override func viewDidLoad() {
super.viewDidLoad()
 
let mapView = MGLMapView(frame: view.bounds)
mapView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
mapView.delegate = self
 
// Denver, Colorado
let center = CLLocationCoordinate2D(latitude: 39.748947, longitude: -104.995882)
 
// Starting point
mapView.setCenter(center, zoomLevel: 10, direction: 0, animated: false)
 
// Colorado’s bounds
let northeast = CLLocationCoordinate2D(latitude: 40.989329, longitude: -102.062592)
let southwest = CLLocationCoordinate2D(latitude: 36.986207, longitude: -109.049896)
colorado = MGLCoordinateBounds(sw: southwest, ne: northeast)
 
view.addSubview(mapView)
}
 
// This example uses Colorado’s boundaries to restrict the camera movement.
func mapView(_ mapView: MGLMapView, shouldChangeFrom oldCamera: MGLMapCamera, to newCamera: MGLMapCamera) -> Bool {
 
// Get the current camera to restore it after.
let currentCamera = mapView.camera
 
// From the new camera obtain the center to test if it’s inside the boundaries.
let newCameraCenter = newCamera.centerCoordinate
 
// Set the map’s visible bounds to newCamera.
mapView.camera = newCamera
let newVisibleCoordinates = mapView.visibleCoordinateBounds
 
// Revert the camera.
mapView.camera = currentCamera
 
// Test if the newCameraCenter and newVisibleCoordinates are inside self.colorado.
let inside = MGLCoordinateInCoordinateBounds(newCameraCenter, self.colorado)
let intersects = MGLCoordinateInCoordinateBounds(newVisibleCoordinates.ne, self.colorado) && MGLCoordinateInCoordinateBounds(newVisibleCoordinates.sw, self.colorado)
 
return inside && intersects
}
}