Open Radar

 
Summary:
The awareness feature that FaceID offers is very awesome. The display dimming is an awesome use case for this but also things like hiding notifications while locked demonstrates the power of this feature (while not being exclusive for FaceID, it becomes a lot more efficient and magical with FaceID in my opinion).

There are a lot of use cases where this awareness could be used to increase the user experience in apps as well. E.g. showing animations that should drag the users attention to updated content or things they need to react to only when the user is actually looking at the screen would make them more effective and less likely to be missed.

Therefore I would love to see this API becoming public and usable by developers. A simple notification for when the user starts and stops looking at the screen and a property on `UIScreen` to check if the user is currently looking at it would already be sufficient for a lot of use cases I guess.

Steps to Reproduce:
 

Expected Results:
 

Actual Results:
 

Version:
11.1.2

Notes: