An activity object you can use to restore the previous contents of your scene's interface.
- iOS 13.0+
- Mac Catalyst 13.0+
- tvOS 13.0+
Before disconnecting a scene, the system asks your delegate for an
NSUser object containing state information for that scene. If you provide that object, the system puts a copy of it in this property. Use the information in the user activity object to restore the scene to its previous state.
The system encrypts your app's state restoration on disk. If the file is unavailable at scene-connection time, perhaps because the device is still locked, the initial value in this property is
nil. When the data becomes available, the system updates the value accordingly.