Question

I have a UIAlertView which appears as a confirmation when a user wants to delete a RegionAnnotation.

I’m having trouble figuring out how to access the RegionAnnotationView that called the UIAlertView which I need in order to delete the RegionAnnotation.

Here’s my broken code – you can see where I’m trying to cast the AlertView’s superview into a RegionAnnotationView (an admittedly bad idea).

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    if(buttonIndex==0)
    {
        NSLog(@"alertView.superview is a %@",alertView.superview);
        RegionAnnotationView *regionView = (RegionAnnotationView *)alertView.superview;
        RegionAnnotation *regionAnnotation = (RegionAnnotation *)regionView.annotation;

        [self.locationManager stopMonitoringForRegion:regionAnnotation.region];
        [regionView removeRadiusOverlay];
        [self.mapView removeAnnotation:regionAnnotation];    
    }

}

Answer 1

Since the annotation is selected before the user can delete it, you can get a reference to the annotation from the map view’s selectedAnnotations property.

In the alert view delegate method, you can do something like this:

if (mapView.selectedAnnotations.count == 0)
{
    //shouldn't happen but just in case
}
else
{
    //since only one annotation can be selected at a time,
    //the one selected is at index 0...
    RegionAnnotation *regionAnnotation 
       = [mapView.selectedAnnotations objectAtIndex:0];

    //do something with the annotation...
}

If the annotation wasn’t selected, another simple alternative is to use an ivar to hold a reference to the annotation that needs to be deleted.

Another option as MSK commented is to use objc_setAssociatedObject.

Regardless, using the superview assuming the view hierarchy is in a certain way is not a good idea.