Restrict MKMapView scrolling

Question

I\'m trying to add a custom image to an MKMapView as an MKOverlayView - I need to restrict users from being able to scroll outside the bounds of th

Answer 1

Anna's (https://stackoverflow.com/a/4126011/3191130) solution in Swift 3.0, I added to an extension:

extension HomeViewController: MKMapViewDelegate {
func mapView(_ mapView: MKMapView, regionDidChangeAnimated animated: Bool) {
    if manuallyChangingMapRect {
        return
    }
    guard let overlay = self.mapOverlay else {
        print("Overlay is nil")
        return
    }
    guard let lastMapRect = self.lastGoodMapRect else {
        print("LastGoodMapRect is nil")
        return
    }

    let mapContainsOverlay = MKMapRectContainsRect(mapView.visibleMapRect, overlay.boundingMapRect)
    if mapContainsOverlay {
        let widthRatio: Double = overlay.boundingMapRect.size.width / mapView.visibleMapRect.size.width
        let heightRatio: Double = overlay.boundingMapRect.size.height / mapView.visibleMapRect.size.height
        // adjust ratios as needed
        if (widthRatio < 0.9) || (heightRatio < 0.9) {
            manuallyChangingMapRect = true
            mapView.setVisibleMapRect(overlay.boundingMapRect, animated: true)
            manuallyChangingMapRect = false
        }
    } else if !overlay.intersects(mapView.visibleMapRect) {
            // Overlay is no longer visible in the map view.
            // Reset to last "good" map rect...
            manuallyChangingMapRect = true
            mapView.setVisibleMapRect(lastMapRect, animated: true)
            manuallyChangingMapRect = false
        }
        else {
            lastGoodMapRect = mapView.visibleMapRect
    }
}
}

To setup the map use this:

override func viewDidLoad() {
    super.viewDidLoad()
    setupMap()
}

func setupMap() {
    mapView.delegate = self
    let radius:CLLocationDistance = 1000000
    mapOverlay = MKCircle(center: getCenterCoord(), radius: radius)
    if let mapOverlay = mapOverlay  {
        mapView.add(mapOverlay)
    }
    mapView.setRegion(MKCoordinateRegionMake(getCenterCoord(), getSpan()), animated: true)
    lastGoodMapRect = mapView.visibleMapRect
}

func getCenterCoord() -> CLLocationCoordinate2D {
    return CLLocationCoordinate2DMake(LAT, LON)
}
func getSpan() -> MKCoordinateSpan {
    return MKCoordinateSpanMake(10, 10)
}