How to know when MKPinAnnotationView pin callout opens/closes

Question

I want to update pin callout (popup) subtitle either realtime, when I receive some new info from server, or at least when callout opens. So far it looks like pin + callout are created only once at...

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

...and then used as-is as long as it exists regardless how many times I tap it closed/open or scroll around keeping it visible. How can I update the subtitle?

Answer 1

Hi,

I can't answer completely beacuse I've never needed to do it but this bit of documentation looks like a pointer in the right direction.

Try just updating the subititle property of your <MKAnnotation> object when a new response comes in from the server and the MapView should update itself?

If not, try removing and re-adding the annotation when the info changes?

Answer 2

edit:: There's a much better solution using key-value observing, which includes adding an observer to the selected property of the MKAnnotationView, then dealing with it appropriately in the callback:

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{

You can view the solution here: http://blog.evandavey.com/2009/07/how-to-detect-when-mkannotation-mkannotationview-is-selected.html

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(old solution)

I had a similar problem. It looks like you've gotten most of it. In your function:

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

Just make sure to add a callback (aka. selector) to each annotation. For me, I actually want a UIButton for them to click on, so I created one and added it as the rightCalloutAccessoryView for the annotation.

UIButton* rightButton = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
        [rightButton addTarget:self
                        action:@selector(showDetails:)
              forControlEvents:UIControlEventTouchUpInside];
        customPinView.rightCalloutAccessoryView = rightButton;

I then created a function called showDetails in whatever delegate you passed to the addTarget variable (in my case self, which is a custom UIViewController).

Now, whenever anyone clicks on any annotation, the showDetails function gets called.

However, I'm having problems with figuring out which specific annotation gets called, as I have many on my map, and the caller of the showDetails function is not the annotation, but the specific UIButton.

I've looked into this solution: http://stackoverflow.com/questions/2329654/clean-solution-to-know-which-mkannotation-has-been-tapped, but it only deals with the event inside viewForAnnotation, which, as you mentioned, only gets called at the creation of each annotation, and not when they get tapped.