The string that identifies that this annotation view is reusable.
- iOS 3.0+
- macOS 10.9+
- tvOS 9.2+
You specify the reuse identifier when you create the view. You use this type later to retrieve an annotation view that was created previously but which is currently unused because its annotation is not on screen.
If you define distinctly different types of annotations (with distinctly different annotation views to go with them), you can differentiate between the annotation types by specifying different reuse identifiers for each one.