Tells the delegate that the specified cell is about to be displayed in the collection view.
- iOS 8.0+
- tvOS 9.0+
The collection view object that is adding the cell.
The cell object being added.
The index path of the data item that the cell represents.
The collection view calls this method before adding a cell to its content. Use this method to detect cell additions, as opposed to monitoring the cell itself to see when it appears.