NSURLAuthenticationChallengeSender protocol represents the interface that the sender of an authentication challenge must implement.
- iOS 8.0+
- macOS 10.10+
- tvOS 9.0+
- watchOS 2.0+
The methods in the protocol are generally sent by a delegate in response to receiving a connection:didReceiveAuthenticationChallenge: or download:didReceiveAuthenticationChallenge:. The different methods provide different ways of responding to authentication challenges.