Using a CALayer as a MKAnnotation delegate for animatable annotations

Question

I want to do an animatable annotation view on a MKMapView but I'd like the animation to be smooth (not like this) and I'm thinking that CoreAnimation might be the best way of doing that.

I'm currently thinking of creating a subclass of CALayer as my MKAnnotation delegate and animate my coordinate property using CoreAnimation. I can even use this as the layer of the MKAnnotationView, I think.

But this is the limit of my understanding about CoreAnimation as I never changed the hierarchy of layers or went more far than doing some 3d transformations to my views layers.

Do you think this is a good approach to the problem?

Do you have any code that you can share to help get there?

Thank you in advance.

Edit: If you believe there's a better approach to doing this like making the MKAnnotation delegate a subclass of NSObject please tell me also. The goal for me is to smoothly animate a coordinate and I thought of QuartzCore framework for that.

Answer 1

Layers are associated with other layers or with views.

MKAnnotation objects are data container objects that descend directly from NSObject. You can't make a layer a "delegate of MKAnnotation"

What you would do is to set up a custom subclass of MKAnnotationView, and add layers and animations to your custom subclass. Your map view would create and return your custom annotation view objects in response to the mapView:viewForAnnotation: map view delegate method.

I haven't tried this myself, but it should work. The docs say that the annotation views are not scaled when the map scales however, so you would have to create your annotation view at a fixed size, or get clever and write code that scales your annotation views when the map scale changes.