Question

I’ve written some code for showing annotations with custom images in a mapview.
My mapview delegate implements this method to customize annotation when they are put in the map:

- (MKAnnotationView *) mapView:(MKMapView *) mapView viewForAnnotation:(id<MKAnnotation>) annotation {
if ([annotation isKindOfClass:[Station class]]) {
    Station *current = (Station *)annotation;
    MKPinAnnotationView *customPinview = [[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:nil];
    if([[current type] compare:FONTANELLA]==NSOrderedSame)
        customPinview.pinColor = MKPinAnnotationColorPurple;
    else{
        int test=current.bici;
        if(test==0)
            customPinview.image = [UIImage imageNamed:@"bicimir.png"];
        else if(test<4)
            customPinview.image = [UIImage imageNamed:@"bicimi.png"];
        else if(test>=4)
            customPinview.image = [UIImage imageNamed:@"bicimig.png"];
    }
    customPinview.animatesDrop = NO;
    customPinview.canShowCallout = YES;
    return customPinview;
}
else{
    NSString *identifier=@"MyLocation";
    MKPinAnnotationView *annotationView = (MKPinAnnotationView *) [_mapView dequeueReusableAnnotationViewWithIdentifier:identifier];
    return annotationView;
}

}

The problem is a strange behavior when I long click on a custom annotation on the map:
The image change and the default red pin is shown.

Why this behavior? And How can I avoid it?

Answer 1

When you want to use a custom image for an annotation view, create a generic MKAnnotationView instead of an MKPinAnnotationView.

The MKPinAnnotationView really likes to display its default image which is a pin.

Rearrange the logic a bit so that for FONTANELLA, it creates an MKPinAnnotationView but for the rest an MKAnnotationView.

Also, you should really implement annotation view re-use for all cases (and the last else part doesn’t make sense since nothing is done if the dequeue doesn’t return anything–you could just do return nil; instead).