Clean solution to know which MKAnnotation has been tapped?

Question

Ok, so you typically have some object X you want to be annotated inside a MKMapView. You do this way:

DDAnnotation *annotation = [[DDAnnotation alloc] initWithCoordinate: poi.geoLocation.coordinate title: @"My Annotation"];
[_mapView addAnnotation: annotation];

Then you create the annotation view inside

- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>)annotation;

And when some callout gets tapped, you handle the event inside:

- (void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)view calloutAccessoryControlTapped:(UIControl *)control;

What's the cleanest solution to pass X down to the latest tap event?

Answer 1

If I'm understanding your question, you should add a reference or property to your DDAnnotation class so that in your calloutAccessoryControlTapped method you can access the object.

@interface DDAnnotation : NSObject <MKAnnotation> {
    CLLocationCoordinate2D coordinate;
    id objectX;
}
@property (nonatomic, readonly) CLLocationCoordinate2D coordinate;
@property (nonatomic, retain) id objectX;

When you create the annotation:

DDAnnotation *annotation = [[DDAnnotation alloc] initWithCoordinate:poi.geoLocation.coordinate title: @"My Annotation"];
annotation.objectX = objectX;
[_mapView addAnnotation: annotation];

Then:

- (void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)view calloutAccessoryControlTapped:(UIControl *)control{

    DDAnnotation *anno = view.annotation;
    //access object via
    [anno.objectX callSomeMethod];
}