How to get a CGPoint from a tapped location?

Question

I\'m working on a graphing calculator app for the iPad, and I wanted to add a feature where a user can tap an area in the graph view to make a text box pop up displaying the

Answer 1

it's probably better and simpler to use a UIGestureRecognizer with the map view instead of trying to subclass it and intercepting touches manually.

Step 1 : First, add the gesture recognizer to the map view:

 UITapGestureRecognizer *tgr = [[UITapGestureRecognizer alloc] 
    initWithTarget:self action:@selector(tapGestureHandler:)];
 tgr.delegate = self;  //also add  to @interface
 [mapView addGestureRecognizer:tgr];

Step 2 : Next, implement shouldRecognizeSimultaneouslyWithGestureRecognizer and return YES so your tap gesture recognizer can work at the same time as the map's (otherwise taps on pins won't get handled automatically by the map):

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer 
shouldRecognizeSimultaneouslyWithGestureRecognizer
    :(UIGestureRecognizer *)otherGestureRecognizer
{
   return YES;
}

Step 3 : Finally, implement the gesture handler:

- (void)tapGestureHandler:(UITapGestureRecognizer *)tgr
{
   CGPoint touchPoint = [tgr locationInView:mapView];

   CLLocationCoordinate2D touchMapCoordinate 
    = [mapView convertPoint:touchPoint toCoordinateFromView:mapView];

   NSLog(@"tapGestureHandler: touchMapCoordinate = %f,%f", 
    touchMapCoordinate.latitude, touchMapCoordinate.longitude);
}