Touch events on MKMapView's overlays

Question

In the app I'm currently designing I have a MKMapView with overlays on it (customized MKPolylines btw) and I would like to be able to detect touch events on these overlays and assign a specific action to each overlay. Could any one help me on this one ? Thanks !

Benja

Answer 1

This can be solved combining How to intercept touches events on a MKMapView or UIWebView objects? and How to determine if an annotation is inside of MKPolygonView (iOS). Add this in viewWillAppear:

WildcardGestureRecognizer * tapInterceptor = [[WildcardGestureRecognizer alloc] init];
tapInterceptor.touchesBeganCallback = ^(NSSet * touches, UIEvent * event) {
    UITouch *touch = [touches anyObject];
    CGPoint point = [touch locationInView:self.mapView];

    CLLocationCoordinate2D coord = [self.mapView convertPoint:point toCoordinateFromView:self.mapView];
    MKMapPoint mapPoint = MKMapPointForCoordinate(coord);
    for (id overlay in self.mapView.overlays) 
    {
        if ([overlay isKindOfClass:[MKPolygon class]])
        {
            MKPolygon *poly = (MKPolygon*) overlay;
            id view = [self.mapView viewForOverlay:poly];
            if ([view isKindOfClass:[MKPolygonView class]])
            {
                MKPolygonView *polyView = (MKPolygonView*) view;
                CGPoint polygonViewPoint = [polyView pointForMapPoint:mapPoint];
                BOOL mapCoordinateIsInPolygon = CGPathContainsPoint(polyView.path, NULL, polygonViewPoint, NO);   
                if (mapCoordinateIsInPolygon) {
                    debug(@"hit!") 
                } else {
                    debug(@"miss!");   
                }
            }
        }
    }

};
[self.mapView addGestureRecognizer:tapInterceptor];

WildcardGestureRecognizer is in the first linked answer. Calling mapView:viewForOverlay: won't be cheap, adding a local cache of those would help.