Using viewForOverlay to return an MKOverlayView but I also need to return an MKCircleRenderer in the same method

Question

I have an MKMapView that I need to display two types of overlay on. One is a tiled overlay that I use a subclass of MKOverlayView and an MKCircleRenderer.

My method is: - (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id <MKOverlay>)overlay but now I need to also render an MKCircle I'm getting an compiler error of: 'Incompatible pointer types returning 'MKCircleRenderer *' from a function with result type 'MKOverlayView * _Nonnull'.

- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id <MKOverlay>)overlay
{

    if ([overlay isKindOfClass:[MKCircle class]]) {
        MKCircleRenderer *circleView = [[MKCircleRenderer alloc] initWithOverlay:overlay];
        circleView.strokeColor = [UIColor redColor];
        circleView.fillColor = [[UIColor redColor] colorWithAlphaComponent:0.4];
        return circleView;
    } else {
        TileOverlayView *view = [[TileOverlayView alloc] initWithOverlay:overlay];
        view.tileAlpha = 1.0;
        return view;
    }
}

That is my code, I'm aware that initWithOverlay is deprecated which I'm working on as another issue.

Can you make your tile view a `MKOverlayRenderer` rather that an overlay view? Then you could implement `rendererForOverlay` rather than `viewForOverlay` And then you can return both renderers from a single method. — Rob, Sep 12 '16 at 09:22
Great help! Thanks @Rob! I just made my `TileOverlayView` a subclass of `MKOverlayRenderer` and it's all working great! If you want to submit as an answer I can accept it :) — LeanneGamble, Sep 12 '16 at 09:49

Rob · Accepted Answer · 2016-09-12T14:31:01.920

The issue is that the tile view is apparently subclassing from MKOverlayView (returned by viewForOverlay), whereas MKCircleRenderer subclasses from the more modern MKCircleRenderer, a subclass of MKOverlayRenderer (returned by rendererForOverlay), not of MKOverlayView.

I'd suggest that you can make your tile view a MKOverlayRenderer subclass rather than an overlay view. That way, rather than viewForOverlay, you can implement rendererForOverlay and return either circle renderer or tile renderer.

Using viewForOverlay to return an MKOverlayView but I also need to return an MKCircleRenderer in the same method

1 Answers1