UICollectionReusableView class defines the behavior for all cells and supplementary views presented by a collection view. Reusable views are so named because the collection view places them on a reuse queue rather than deleting them when they are scrolled out of the visible bounds. Such a view can then be retrieved and repurposed for a different set of content.
- iOS 6.0+
- tvOS 6.0+
This class is intended to be subclassed. Most methods defined by this class have minimal or no implementations. You are not required to override any of the methods but can do so in cases where you want to respond to changes in the view’s usage or layout.