reuseIdentifier
The string that identifies that the annotation view is reusable.
Declaration
var reuseIdentifier: String? { get }Discussion
You specify the reuse identifier when you create the view. You use this type to retrieve an annotation view that MapKit isn’t currently using because its annotation isn’t onscreen.
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.