Question

I wrote this code to create a custom annotation image

 - (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation
{
    static NSString *google = @"googlePin";
    if ([annotation isKindOfClass:[myClass class]])
    {
        MKAnnotationView *annotationView = [mapView dequeueReusableAnnotationViewWithIdentifier:google];
        if (!annotationView)
        {
            annotationView = [[MKAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:google];
            annotationView.image = [UIImage imageNamed:@"pin.png"];
        }
        return annotationView;
    }
    return nil;

}

The image is appearing on the map; however when I click on it nothing happen, no title nor subtitle.

Do you guys have any idea?

Answer 1

When you override viewForAnnotation, you have to set canShowCallout to YES (the default on a new view you alloc/init is NO).

If you don’t override that delegate method, the map view creates a default red pin with canShowCallout already set to YES.

However, even with canShowCallout set to YES, the callout will still not appear if the annotation’s title is nil or blank (empty string).

(But again, if the title is not nil and not blank, the callout won’t show unless canShowCallout is YES.)

MKAnnotationView *annotationView = [mapView dequeueReusableAnnotationViewWithIdentifier:google];
if (!annotationView)
{
    annotationView = [[MKAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:google];
    annotationView.image = [UIImage imageNamed:@"pin.png"];
    annotationView.canShowCallout = YES;  // <-- add this
}
else
{
    // unrelated but should handle view re-use...
    annotationView.annotation = annotation; 
}

return annotationView;