Returns the operation queue that launched the current operation.
- iOS 4.0+
- macOS 10.6+
- UIKit for Mac 13.0+Beta
- tvOS 9.0+
- watchOS 2.0+
The operation queue that started the operation or
nil if the queue could not be determined.
You can use this method from within a running operation object to get a reference to the operation queue that started it. Calling this method from outside the context of a running operation typically results in
nil being returned.