- (id)initWithMapRect:(MKMapRect)mapRect
{
    MKMapPoint nwMapPoint = MKMapPointMake(mapRect.origin.x, mapRect.origin.y);
    MKMapPoint seMapPoint = MKMapPointMake(mapRect.origin.x + mapRect.size.width, mapRect.origin.y + mapRect.size.height);
    CLLocationCoordinate2D nwCoord = MKCoordinateForMapPoint(nwMapPoint);
    CLLocationCoordinate2D seCoord = MKCoordinateForMapPoint(seMapPoint);
    return [self initWithWithNorth:nwCoord.latitude
                              west:nwCoord.longitude
                             south:seCoord.latitude
                              east:seCoord.longitude];
}