Tells you when the scene’s size has changed.
- iOS 7.0+
- macOS 10.9+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 3.0+
The old size of the scene, in points.
This method is intended to be overridden in a subclass. Typically, you use this method to adjust the positions of nodes in the scene.