UICollection protocol defines methods that allow you to manage the selection and highlighting of items in a collection view and to perform actions on those items. The methods of this protocol are all optional.
- iOS 6.0+
- tvOS 9.0+
Many methods of this protocol take
NSIndex objects as parameters. To support collection views, UIKit declares a category on
NSIndex that enables you to get the represented item index and section index, and to construct new index path objects from item and index values. Because items are located within their sections, you usually must evaluate the section index number before you can identify the item by its index number.