MapView Annotation not dragging - iphone

Question

I am trying to implement a draggable "pin" (actually a custom icon) in a map view. This is the delegate code that I have:
-(MKAnnotationView *) mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation {
MKAnnotationView *aView;
aView=(MKAnnotationView *) [mvMap dequeueReusableAnnotationViewWithIdentifier:annotation.title];
if (aView==nil)
aView=[[[MKAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:annotation.title] autorelease];
else
aView.annotation=annotation;
[aView setImage:[UIImage imageNamed:selIcon]];
aView.canShowCallout=TRUE;
[aView setDraggable:YES];
return aView;
}
- (void)mapView:(MKMapView *)mapView didAddAnnotationViews:(NSArray *)views {
MKAnnotationView *aV;
for (aV in views) {
CGRect endFrame = aV.frame;
int xDelta=0;
xDelta=sIcons.selectedSegmentIndex*61+22;
aV.frame = CGRectMake(aV.frame.origin.x-145+xDelta, aV.frame.origin.y - 150.0, aV.frame.size.width, aV.frame.size.height);
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:0.7];
[UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
[aV setFrame:endFrame];
[UIView commitAnimations];
}
}
-(void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)view didChangeDragState:(MKAnnotationViewDragState)newState fromOldState:(MKAnnotationViewDragState)oldState {
if (oldState == MKAnnotationViewDragStateDragging) {
addAnnotation *annotation = (addAnnotation *)view.annotation;
annotation.subtitle = [NSString stringWithFormat:#"%f %f", annotation.coordinate.latitude, annotation.coordinate.longitude];
}
if (newState == MKAnnotationViewDragStateEnding) {
CLLocationCoordinate2D droppedAt = view.annotation.coordinate;
NSLog(#"dropped at %f,%f", droppedAt.latitude, droppedAt.longitude);
}
}
The problem is that didChangeDragState is never being called (I've set a breakpoint in the routine to be sure). Everything else is working fine. My icons animate into the view, etc. When I tap the icon and hold my finger down the icon stays in place (the map doesn't move either which makes me think that I've actually hit the icon). Am I missing some kind of initialization?

Answer 1

Got it! The problem was in the interface file of my custom annotation class. The offending line read:
#property (nonatomic,readonly) CLLocationCoordinate2D coordinate;
It has to read:
#property (nonatomic,readwrite,assign) CLLocationCoordinate2D coordinate;
I guess that it has to have read/write capability.

Answer 2

Use MKPinAnnotationView instead of MKAnnotationView.
MKPinAnnotationView *pin = (MKPinAnnotationView *)[mapView dequeueReusableAnnotationViewWithIdentifier:#"purple_pin"];
if (pin==nil)
{
pin = [[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:#"purple_pin"];} else {
pin.annotation=annotation;
}
pin.pinColor = MKPinAnnotationColorPurple;
pin.draggable = TRUE;
return pin;

Answer 3

This is a tricky one! I've just implemented something similar (though I subclassed MKAnnotationView) and when I tried adding the annotationView:didChange delegate method to my view controller it didn't get called even though I was able to drag the annotation view??
I also copy/pasted your code into my view controller and it worked straight out of the box, with the delegate method being called and all!
The only thing I can think of is that instead of passing mvMap to dequeueReusableAnnotationViewWithIdentifier: try passing the mapView object that is supplied by the delegate method. Based on the code you provided above I am unable to tell if they are the same object so it might be worth a shot?
aView=(MKAnnotationView *) [mvMap dequeueReusableAnnotationViewWithIdentifier:annotation.title];
[EDIT TO ADD MY CODE AS REFERENCE]
- (MKAnnotationView *)mapView:(MKMapView *)theMapView viewForAnnotation:(id<MKAnnotation>)annotation
{
static NSString* ParkAnnotationIdentifier = #"ParkAnnotationIdentifier";
MKAnnotationView* parkAnnotationView = (MKAnnotationView *)[mapView dequeueReusableAnnotationViewWithIdentifier:ParkAnnotationIdentifier];
if (!parkAnnotationView)
{
MKAnnotationView *annotationView = [[[MKAnnotationView alloc] initWithAnnotation:annotation
reuseIdentifier:ParkAnnotationIdentifier] autorelease];
UIImage *imageIcon = [UIImage imageNamed:#"scooterIcon.png"];
annotationView.image = imageIcon;
annotationView.draggable = YES;
return annotationView;
}
else
{
parkAnnotationView.annotation = annotation;
}
return parkAnnotationView;
}

Answer 4

if you are using a subview of MKPinAnnotationView and are overriding setSelected(), make sure you call super.setSelected()