Returns the starting layout information for a supplementary view being inserted into the collection view.
- iOS 6.0+
- tvOS 9.0+
A string that identifies the type of supplementary view.
The index path of the item being inserted.
A layout attributes object that describes the position at which to place the corresponding supplementary view.
This method is called after the
prepare(for method and before the
finalize method for any supplementary views that are about to be inserted. Your implementation should return the layout information that describes the initial position and state of the view. The collection view uses this information as the starting point for any animations. (The end point of the animation is the view’s new location in the collection view.) If you return
nil, the layout object uses the item’s final attributes for both the start and end points of the animation.
The default implementation of this method returns