Detecting Touches on Mkoverlay in iOS7 (Mkoverlayrenderer)

Detecting touches on MKOverlay in iOS7 (MKOverlayRenderer)

I've done it.

Thanks to incanus and Anna!

Basically I add a TapGestureRecognizer to the MapView, convert the point tapped to map coordinates, go through my overlays and check with CGPathContainsPoint.

Adding TapGestureRecognizer. I did that trick of adding a second double tap gesture, so that the single tap gesture isn't fired when doing a double tap to zoom on map. If anyone knows a better way, I'm glad to hear!

UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleMapTap:)];
tap.cancelsTouchesInView = NO;
tap.numberOfTapsRequired = 1;

UITapGestureRecognizer *tap2 = [[UITapGestureRecognizer alloc] init];
tap2.cancelsTouchesInView = NO;
tap2.numberOfTapsRequired = 2;

[self.mapView addGestureRecognizer:tap2];
[self.mapView addGestureRecognizer:tap];
[tap requireGestureRecognizerToFail:tap2]; // Ignore single tap if the user actually double taps

Then, on the tap handler:

-(void)handleMapTap:(UIGestureRecognizer*)tap{
    CGPoint tapPoint = [tap locationInView:self.mapView];

    CLLocationCoordinate2D tapCoord = [self.mapView convertPoint:tapPoint toCoordinateFromView:self.mapView];
    MKMapPoint mapPoint = MKMapPointForCoordinate(tapCoord);
    CGPoint mapPointAsCGP = CGPointMake(mapPoint.x, mapPoint.y);

    for (id<MKOverlay> overlay in self.mapView.overlays) {
        if([overlay isKindOfClass:[MKPolygon class]]){
            MKPolygon *polygon = (MKPolygon*) overlay;

            CGMutablePathRef mpr = CGPathCreateMutable();

            MKMapPoint *polygonPoints = polygon.points;

            for (int p=0; p < polygon.pointCount; p++){
                MKMapPoint mp = polygonPoints[p];
                if (p == 0)
                    CGPathMoveToPoint(mpr, NULL, mp.x, mp.y);
                else
                    CGPathAddLineToPoint(mpr, NULL, mp.x, mp.y);
            }

            if(CGPathContainsPoint(mpr , NULL, mapPointAsCGP, FALSE)){
                // ... found it!
            }

            CGPathRelease(mpr);
        }
    }
}

I could ask for the MKPolygonRenderer which already has the "path" property and use it, but for some reason it is always nil. I did read someone saying that I could call invalidatePath on the renderer and it does fill the path property but it just seems wrong as the point is never found inside any of the polygons. That is why I rebuild the path from the points. This way I don't even need the renderer and just make use of the MKPolygon object.

Detecting a point in a MKPolygon broke with iOS7 (CGPathContainsPoint)

For some reason (possibly a bug), the path property returns NULL in the current release of iOS 7.

A workaround is to construct your own CGPathRef from the points of the polygon.

With this method, you don't need a reference to the MKPolygonView or the MKPolygonRenderer.

For example:

CGMutablePathRef mpr = CGPathCreateMutable();

MKMapPoint *polygonPoints = myPolygon.points;
//myPolygon is the MKPolygon

for (int p=0; p < myPolygon.pointCount; p++)
{
    MKMapPoint mp = polygonPoints[p];
    if (p == 0)
        CGPathMoveToPoint(mpr, NULL, mp.x, mp.y);
    else
        CGPathAddLineToPoint(mpr, NULL, mp.x, mp.y);
}

CGPoint mapPointAsCGP = CGPointMake(mapPoint.x, mapPoint.y);
//mapPoint above is the MKMapPoint of the coordinate we are testing.
//Putting it in a CGPoint because that's what CGPathContainsPoint wants.

BOOL pointIsInPolygon = CGPathContainsPoint(mpr, NULL, mapPointAsCGP, FALSE);

CGPathRelease(mpr);

This should work on iOS 6 as well.

However, you may want to do this manual construction only if the overlay view's path property returns NULL.

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