Adds an animation object for the specified key.
- iOS 8.0+
- macOS 10.8+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 3.0+
The animation object to be added.
An string identifying the animation for later retrieval. You may pass
nilif you don’t need to reference the animation later.
Newly added animations begin executing after the current run loop cycle ends.
SceneKit does not define any requirements for the contents of the
key parameter—it need only be unique among the keys for other animations you add. If you add an animation with an existing key, this method overwrites the existing animation.