I have an app that displays overlays on top of an AVCaptureVideoPreviewLayer (basically AR without ARKit), and my users have repeatedly requested a button that will allow them to capture a screenshot of both the video and the overlays and surrounding UI with a single tap. However, I cannot find a way to actually take such a screenshot.
I have tried the usual methods of rendering views to images, such as calling drawViewHierarchyInRect on my top level view or calling renderInContext on the same view's layer. These all work perfectly to capture the overlays and the surrounding UI elements, but there is nothing but black where the video preview's contents should be.
snapshotViewAfterScreenUpdates: does capture exactly what I want, but snapshot views cannot be written to an image. From what I understand that's an intentional security decision by Apple.
I've considered using ReplayKit to take a very short screen recording and then using an AVAssetImageGenerator to grab a frame from that video, but I don't think that's how those APIs were intended to be used and it's an additional permission to request from the user. I would really rather not do this if there is any alternative (and I'm not even sure it would work).
Is there any reasonable method to render a view hierarchy to an image in such a way as to capture the contents of any video preview layers found within that hierarchy?