How to make custom MKAnnotation draggable - ios

Question

I need MKAnnotation with different pin image.
So I created following:
#interface NavigationAnnotation : NSObject <MKAnnotation>
- (id)initWithName:(NSString*)name address:(NSString*)address coordinate:(CLLocationCoordinate2D)coordinate;
...
#interface NavigationAnnotation ()
#property (nonatomic, copy) NSString *name;
#property (nonatomic, copy) NSString *address;
#property (nonatomic, assign) CLLocationCoordinate2D theCoordinate;
#end
#implementation NavigationAnnotation
- (id)initWithName:(NSString*)name address:(NSString*)address coordinate:(CLLocationCoordinate2D)coordinate {
if ((self = [super init])) {
if ([name isKindOfClass:[NSString class]]) {
self.name = name;
} else {
self.name = #"Unknown charge";
}
self.address = address;
self.theCoordinate = coordinate;
}
return self;
}
- (NSString *)title {
return _name;
}
- (NSString *)subtitle {
return _address;
}
- (CLLocationCoordinate2D)coordinate {
return _theCoordinate;
}
And add it like this:
- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation{
static NSString *identifier_OrderAnnotation = #"NavigateAnnotation";
if ([annotation isKindOfClass:[MKUserLocation class]])
return nil;
if ([annotation isKindOfClass:[NavigationAnnotation class]]) {
MKAnnotationView *annotationView = (MKAnnotationView *) [_mapView dequeueReusableAnnotationViewWithIdentifier:identifier_OrderAnnotation];
if (annotationView == nil) {
annotationView = [[MKAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:identifier_OrderAnnotation];
annotationView.enabled = YES;
annotationView.canShowCallout = YES;
annotationView.draggable = YES;
annotationView.image = [UIImage imageNamed:#"myimage.png"];
} else {
annotationView.annotation = annotation;
}
return annotationView;
}
}
Annotation shows on map fine but it is not draggable from some reason :(

Answer 1

As already mentioned, for an annotation to be draggable, it must implement a setCoordinate: method.
Additionally, since iOS 7, you may also need to implement the mapView:annotationView:didChangeDragState: method (see Draggable Pin does not have a fixed position on map and iOS MapKit dragged annotations (MKAnnotationView) no longer pan with map).
You can either implement the setCoordinate: method explicitly yourself or just declare a writeable coordinate property (named exactly like that) and synthesize it (and the getter and setter methods will be automatically implemented for you).
(Note that if you use the pre-defined MKPointAnnotation class, you don't need to do this because that class already implements a settable coordinate property.)
In your NavigationAnnotation class, to implement the explicit, manual solution to work with the existing theCoordinate property, just add the setCoordinate: method to your class implementation (keep the existing getter method):
-(void)setCoordinate:(CLLocationCoordinate2D)newCoordinate
{
self.theCoordinate = newCoordinate;
}
You may also need to implement the didChangeDragState: method in the class that implements the map view delegate (the same one that has the viewForAnnotation method) otherwise after dragging, the annotation view will hover in-place above the map even while it is panned or zoomed underneath. An example implementation of the method as given by Chris K. in his answer:
- (void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)annotationView didChangeDragState:(MKAnnotationViewDragState)newState fromOldState:(MKAnnotationViewDragState)oldState
{
if (newState == MKAnnotationViewDragStateStarting)
{
annotationView.dragState = MKAnnotationViewDragStateDragging;
}
else if (newState == MKAnnotationViewDragStateEnding || newState == MKAnnotationViewDragStateCanceling)
{
annotationView.dragState = MKAnnotationViewDragStateNone;
}
}

Answer 2

Just went through this issue...
After some struggling, reason was different (title, coordinate were ok), so adding possible cause here
In my annotation view, I did override - (void) setSelected:(BOOL)selected
Without calling [super setSelected:selected];
This prevented the dragging from occuring...