Recording video of the screen in AR application

I’m creating an AR application in UE4. how can I implement the video recording capabilities and screenshots from the android phone and iOS screen in my at. It would be maximally progressive to ask the possibility of recording 2 files, this is the video from the phone’s camera and also a separate file itself, the content with the alpha channel that would be able to edit the recorded work session in the application.

In this case, you can use Screen Recorder of IOS, is native, but don’t record alpha… Sorry
I’m trying to figure out the same process, but I need to record the front camera of iPhone and save the videos on own iPhone. Someone can give one light. Thanks, folks…