MKMapView - Limit map scroll to a square overlay - ios

Question

I have a MKMapView with a square overlay described as:
CLLocationCoordinate2D coordsBg[5]={
CLLocationCoordinate2DMake(31.750865,35.180882),
CLLocationCoordinate2DMake(31.740331,35.180882),
CLLocationCoordinate2DMake(31.740331,35.165452),
CLLocationCoordinate2DMake(31.750865,35.165452),
CLLocationCoordinate2DMake(31.750865,35.180882)
};
MKPolygon *bg=[MKPolygon polygonWithCoordinates:coordsBg count:5];
[map addOverlay:bg];
I wish to limit the user from scrolling outside of the overlay.
Can I limit the MKMapView scroll view for that? Or there is an other method?
Thanks
Shani

Answer 1

After Few hours of banging my head, I got to this solution that work great for me.
It mixes up :
This post: set the zoom level of an mkmapview
And This link: restrict mkmapview scrolling from #Anna Karenina comment to my question.
And This is my code:
- (void)mapView:(MKMapView *)mapView regionWillChangeAnimated:(BOOL)animated
{
lastGoodMapRect = mapView.visibleMapRect;
lastGoodRegion = mapView.region;
}
- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated
{
if (manuallyChangingMapRect) {
manuallyChangingMapRect=NO;
return;
}
if( [mapView zoomLevel] > 16 )
{
[mapView setCenterCoordinate:lastGoodRegion.center zoomLevel:16 animated:YES];
}
MKMapRect visibleRect = mapView.visibleMapRect;
MKMapRect OverlayRect = bg.boundingMapRect;
MKMapRect intersectionRect = MKMapRectIntersection(visibleRect,OverlayRect);
//you can change the min and max zoom off course
if(!MKMapRectEqualToRect(visibleRect,intersectionRect)){
if( [mapView zoomLevel] < 15){
[mapView setCenterCoordinate:lastGoodRegion.center zoomLevel:15 animated:YES];
}else if( [mapView zoomLevel] > 16 )
{
[mapView setCenterCoordinate:lastGoodRegion.center zoomLevel:16 animated:YES];
}else{
manuallyChangingMapRect=YES;
[mapView setVisibleMapRect:lastGoodMapRect animated:YES];
}
}
}