Adds an identifiable action to the list of actions executed by the node.
- iOS 7.0+
- macOS 10.9+
- tvOS 9.0+
- watchOS 3.0+
The action to perform.
A unique key used to identify the action.
This method is identical to
run(_:), but the action is stored so that it can be retrieved later. If an action using the same key is already running, it is removed before the new action is added.