iOS - How to limit the MapView to a specific region?

Question

I have the following problem:

I have a \"drawn map\" (image) which I add to the MapView as an Overlay. No Problem with that.. but I need to limit the MapView to the

Answer 1

I know this is a pretty old question, but to avoid the infinite loop you could try something like this: https://stackoverflow.com/a/4126011/1234011

Basically set a flag to prevent the callback from firing again if it was you who set the value.

• Ken

Answer 2

By implementing :

-(void) mapView:(MKMapView *)mapView regionWillChangeAnimated:(BOOL)animated

You should be able to reset region to your specific one.

Look at that answer to have an example of how to do this.

---

Another solution, that brings more precise events but is more complex (I'm currently using this successfully for another need) is to subclass MKMapView and override UIScrollViewDelegate protocol.

If you do that, make sure to call super implementation like that :

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
  if ([super respondsToSelector:@selector(scrollViewWillBeginDragging:)])
    [super scrollViewWillBeginDragging:scrollView];
  // do what you want
}

Note: While the protocol is public, MKMapView implementation is unknown and might differ with iOS versions, so it is more safe to check with respondsToSelector: before. You must call super implementations or Map will just not work properly.

Answer 3

After trying different ways of limited MKMapView I've concluded that using mapDidChange, and resetting if you're center point goes outside of the boundaries works best, with animated: YES

Here's how I do it (Using the New Zealand lat/Long span/center).

- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated{ 
  if ((mapView.region.span.latitudeDelta > 15.589921 ) || (mapView.region.span.longitudeDelta > 175.836914) ) {
    CLLocationCoordinate2D centerCoord = CLLocationCoordinate2DMake(-41.162114, 172.836914);

    MKCoordinateSpan spanOfNZ = MKCoordinateSpanMake(13.589921, 14.062500 );

    MKCoordinateRegion NZRegion = MKCoordinateRegionMake(centerCoord, spanOfNZ);

    [mapView setRegion: NZRegion animated: YES];
  }

 if (abs(abs(mapView.region.center.latitude) - 41.162114) > (13.589921 / 2) ) {
    CLLocationCoordinate2D centerCoord = CLLocationCoordinate2DMake(-41.162114, 172.836914);

    MKCoordinateSpan spanOfNZ = MKCoordinateSpanMake(13.589921, 14.062500 );

    MKCoordinateRegion NZRegion = MKCoordinateRegionMake(centerCoord, spanOfNZ);

    [mapView setRegion: NZRegion animated: YES];

  }

  if (abs(abs(mapView.region.center.longitude) - 172.836914) > (14.062500 / 2) ) {
    CLLocationCoordinate2D centerCoord = CLLocationCoordinate2DMake(-41.162114, 172.836914);

     MKCoordinateSpan  spanOfNZ = MKCoordinateSpanMake(13.589921, 14.062500 );

     MKCoordinateRegion NZRegion = MKCoordinateRegionMake(centerCoord, spanOfNZ);

     [mapView setRegion: NZRegion animated: YES];
  }
}