Removes and returns the last element of the collection.
- iOS 7.0+
- macOS 10.9+
- UIKit for Mac 13.0+Beta
- tvOS 9.0+
- watchOS 2.0+
- Xcode 10.0+
The last element of the collection if the collection is not empty; otherwise,
Calling this method may invalidate all saved indices of this collection. Do not rely on a previously stored index value after altering a collection with any operation that can change its length.