How to limit map bounds in mapbox MGLMapView? - ios

Question

I'm using mapbox-iOS-SDK 3.2.3 and can't find any properties or smth like this to control the map bounds. I need to limit the visible area for the user. Is it possible in current SDK version?

Answer 1

There's nothing built in to the current version of Mapbox that looks like it would do what you want. You might be able to get something like it by
Implementing mapViewRegionIsChanging: or mapView:regionDidChangeAnimated: in the map view delegate
In those methods, check the current region. If it's outside the desired area, reset the map view to something inside the desired region. That is, as soon as the map view starts to move outside the region, make it go back.
This would probably work but it might make the view "stutter" if the user tries to scroll outside the target region. I don't know what your app does, but it might be worth considering (a) whether this is actually necessary and (b) whether there might be a better way to avoid whatever problem you expect than restricting map view scrolling.

Answer 2

I took the idea from #Tom Harrington and implemented the delegate with the goal of seeing how much stutter or animation jankiness there was while keeping a user within a known Mapbox bound. I upvoted his answer, but also wanted to share this example.
Here is a Swift delegate that fills out the delegate for mapViewRegionIsChanging
the main goal is to test if the experience is still pleasing to the customer (yes)
Can the delegate properly keep the user within bounds without calling the delegate too often? (still needs to be verified)
Uses Balboa Park, as a square Mapbox MGLCoordinateBounds
Only checks if the customer scrolls too far north
The concept of too far is checked by some tolerance, epsilon
Checking out of bounds on four sides should be straightforward
func mapViewRegionIsChanging (mapView: MGLMapView) {
let viewBounds = mapView.visibleCoordinateBounds
// Set the map's bounds to Balboa Park, San Diego
let boundsBalboaPark = MGLCoordinateBounds(
sw: CLLocationCoordinate2D(latitude: 32.71942, longitude: -117.15914),
ne: CLLocationCoordinate2D(latitude: 32.74093, longitude: -117.13374))
let deltaNorth = viewBounds.ne.latitude - boundsBalboaPark.ne.latitude
let epsilon = 0.025 // Magic number for tolerance of how far 'north' we allow (in degrees); Q.E.D meters
if( deltaNorth > epsilon) {
mapView.setVisibleCoordinateBounds(boundsBalboaPark, animated: true)
}
}
This animation shows moving the mapView too far north of Balboa Park. The stutter you see is real, but acceptable.