iOS 7 MKOverlayRenderer Not Working

Question

I'm updating an iOS 6 app for iOS 7 and discovered that the way overlays are handled has completely changed in iOS 7.

We're drawing a light grey overlay over the entire map. In iOS 6 everything works perfectly, in iOS 7 we get no overlay.

In viewDidLoad I have the following:

CLLocationCoordinate2D worldCoords[4] = { {90,-180}, {90,180}, {-90,180}, {-90,-180} };
MKPolygon *worldOverlay = [MKPolygon polygonWithCoordinates:worldCoords
                                                      count:4];
[self.mapView addOverlay:worldOverlay];

Then, for iOS 6 . . .

- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id<MKOverlay>)overlay
{
    if (![overlay isKindOfClass:[MKPolygon class]]) {
        return nil;
    }
    MKPolygon *polygon = (MKPolygon *)overlay;
    MKPolygonView *view = [[MKPolygonView alloc] initWithPolygon:polygon];
    view.fillColor = [[UIColor darkGrayColor] colorWithAlphaComponent:0.4];
    return view;
}

For iOS 7 . . .

- (MKOverlayRenderer *)mapView:(MKMapView *)mapView rendererForOverlay:(id<MKOverlay>)overlay
{
    if (![overlay isKindOfClass:[MKPolygon class]]) {
        return nil;
    }
    MKPolygon *polygon = (MKPolygon *)overlay;
    MKPolygonRenderer *renderer = [[MKPolygonRenderer alloc] initWithPolygon:polygon];
    renderer.fillColor = [[UIColor darkGrayColor] colorWithAlphaComponent:0.4];    
    return renderer;
}

Using breakpoints, I verified that the mapView:rendererForOverlay: method is being called and that the renderer object it's returning has the fillColor property set correctly.

Any thoughts as to why we're not seeing the overlay?

Answer 1

All of your code is absolutely valid - I plugged it into my test map controller and it works perfectly if I do one small change:

    CLLocationCoordinate2D worldCoords[4] = { {43,-100}, {43,-80}, {25,-80}, {25,-100} };

So, the problem is not in the renderer per se. I believe it has something to do with specifying 180th Meridian - Apple has made some changes to support regions spanning the 180th Meridian in iOS7. I don't need it since focusing exclusively on North America so I skipped it but there is a 2013 WWDC video where they talk about it - see What's New in MapKit session around 4:42: https://developer.apple.com/wwdc/videos/

Cheers,