I think at least in snap it makes sense, the communications are suppose to be ethereal and disappear after reading, I like to know when someone screenshots something and its no longer ethereal
Snapchat advertises that they detect screenshots. They try. But they're well aware that they can't actually know.
For example, their bug bounty program policy helpfully informs you that "screenshot detection avoidance" is not considered a vulnerability: https://hackerone.com/snapchat . That's because it's always possible.
Yes, iOS has userDidTakeScreenshotNotification for that.
https://developer.apple.com/documentation/uikit/uiapplicatio...
Would be nice if the user could disable that.
I think at least in snap it makes sense, the communications are suppose to be ethereal and disappear after reading, I like to know when someone screenshots something and its no longer ethereal
Yes, Snapchat does this. Apps absolutely have the ability to know when a screenshot is taken.
Snapchat advertises that they detect screenshots. They try. But they're well aware that they can't actually know.
For example, their bug bounty program policy helpfully informs you that "screenshot detection avoidance" is not considered a vulnerability: https://hackerone.com/snapchat . That's because it's always possible.