When adapting a UIKit app for iPhone Duo, is there a supported API for observing the hinge/fold angle continuously during an unfolding transition?
For example, if the device is partially unfolded at approximately 23°, can an app detect or respond to that specific angle (or ranges of angles) and update/freeze its UI accordingly, or does UIKit expose only discrete pose/state transitions?
Additionally, can an app distinguish between unfolding while the device is oriented in portrait versus landscape and provide different adaptive layouts or transition behavior for each?
I’m specifically interested in what device posture/hinge information is exposed to UIKit during the interactive unfolding transition, and whether developers should design around continuous hinge-angle changes or only the system-provided size, orientation, trait, and pose/state changes.