How do i restrict panning and restrict zooming out of a certain area of apple maps in MapKit? - ios

Question

I am currently making an app with a map that should focus on a certain location only. I would like the user to not be able to zoom out or pan out of this area so they can keep their focus on the image overlay that i have put over this area.
In order to get the app to start off from the location that i want and not some random map, I used a tutorial from Ray Wenderlich: https://www.raywenderlich.com/425-mapkit-tutorial-overlay-views
How would I acoomplish my task based on the code that is written in the tutorial above? I have completed the tutorial, so I am looking for help in adding any code and identifying where and what kind of code to put.
I found other tutorials on this topic unhelpful because they were for other map types like Google maps or MapBox. The apple website about MapKit and MaximumZ does not help me very much either.
I am a beginner in XCode and Swift, and have only had little bit of experience in Python previously. I was hoping limiting the zoom and user access to parts of the maps would be easier...
override func viewDidLoad() {
super.viewDidLoad()
let latDelta = park.overlayTopLeftCoordinate.latitude -
park.overlayBottomRightCoordinate.latitude
// Think of a span as a tv size, measure from one corner to another
let span = MKCoordinateSpanMake(fabs(latDelta), 0.0)
let region = MKCoordinateRegionMake(park.midCoordinate, span)
mapView.region = region
}
This is what I have so far for getting the app to startup on the location that I want, using a rectangle that bounds the area that I am looking to restrict the user to.

Answer 1

The MKMapView has a delegate MKMapViewDelegate. This protocol has a function called:
func mapViewDidChangeVisibleRegion(_:)
This method is called whenever the user scrolls or zooms the map. In this method you can specify the behavior of the map. You can, for instance set a specific region that you want the map to zoom into and specify the maximum level of zoom allowed.
In the function mapViewDidChangeVisibleRegion(_:) you can then check to what latitudeDelta and longitudeDelta the map can zoom into. If the delta's go below or above a certain level you can lock the zooming by setting the region with something like this:
func mapViewDidChangeVisibleRegion(_ mapView: MKMapView) {
if mapView.region.span.latitudeDelta < 0.4 {
regionSpan = MKCoordinateSpan(latitudeDelta: 0.4, longitudeDelta: 0.5)
let mapRegion = MKCoordinateRegion(center: self.centerCoordinate, span: self.regionSpan)
self.trackMapView.setRegion(mapRegion, animated: true)
}
}