Is it possible to hide or blur the whole screen or part of the screen of my app when the user is taking a screenshot as of iOS 11? If I could get the event before the capture I would be able to hide the view, but according to my research, there is an event only after the capture.
All StackOverflow and Google search results say preventing screenshot is impossible, but since I had seen an app that did that (though I am not sure it still works on iOS 11), I cannot easily tell the client it is impossible.
When I had an iPad (iOS 10), I could not capture the screen of one Bitcoin wallet app. I tried to save its recovery key screen, but the screenshot image was blurred or something (I cannot remember exactly). I think the app's name was Bread. Unfortunately, right now, I do not have an iOS device, so I cannot test it.
How did the app do it? Did the app modify the captured image after the screenshot event? Is it possible to modify the screenshot silently?