NSURLSession protocol defines the methods that a delegate of an
URLSession object can implement to handle task-level events specific to data tasks and upload tasks. Your session delegate should also implement the methods in the
URLSession protocol to handle task-level events that are common to all task types, and methods in the
URLSession protocol to handle session-level events.
- iOS 7.0+
- macOS 10.9+
- tvOS 9.0+
- watchOS 2.0+