Returns an array of index paths representing the decoration views to add.
- iOS 7.0+
- tvOS 9.0+
The specific type of decoration view.
An array of
NSIndex objects indicating the location of the new decoration views or an empty array if you do not want to add any decoration views.
The collection view calls this method whenever you add cells or sections to the collection view. Implementing this method gives your layout object an opportunity to add new decoration views to complement the additions.