How to define the order of overlapping MKAnnotationViews?

Question

I have several MKAnnotations (and their corresponding views) in my map, and it sometimes gets really crowded. Now, the annotations in my app come in two flavors: some are bound to stay where they are, while others will move as time goes on. I'd prefer to have the more stable ones visually in the background and the moving ones to always pass in front of them.

One would think, perhaps, that the annotations most recently added to the map would end up to the front (or alternatively at the very back, at least) but this just doesn't seem to be the rule. As far as I can tell, I create and add ALL the non-moving annotations first, and then add some newly-instantiated moving annotations, but many of them (although not all!) end up drawn under the perpetually stock-still ones.

Interestingly, when time goes by, and yet new moving annotations are created, they tend to gravitate more to the top than the first ones - even if all moving annotation objects were created only after the nonmoving parts were already added to the map.

Does anyone know a trick to alter this strange natural order of the annotation views on the map? I tried to search the Map Kit API, but it doesn't seem to speak of such a thing.

Answer 1

Ok, so for solution use method from MKMapViewDelegate

- (void)mapView:(MKMapView *)mapView didAddAnnotationViews:(NSArray *)views
 

In this method you should rearrange AnnotationView after it was added to mapKit View. So, code may looks like this:

- (void)mapView:(MKMapView *)mapView didAddAnnotationViews:(NSArray *)views {
   for (MKAnnotationView * annView in views) {
      TopBottomAnnotation * ann = (TopBottomAnnotation *) [annView annotation];
      if ([ann top]) {
         [[annView superview] bringSubviewToFront:annView];
      } else {
         [[annView superview] sendSubviewToBack:annView];
      }
   }

}

This works for me.

Answer 2

I'm finding that this reordering the annotation views causes the callout that pops up when one is clicked to no longer be on top of all the annotations. I've even tried refining it so that instead of bringSubviewToFront and sendSubviewToBack, I use insertSubview:aboveSubview and insertSubview:belowSubview: where the second argument is the first annotationView in the list. This would seem to cause much less front to back scattering, but the call outs still pop up under some annotations.