How to detect when the user takes a screenshot

Swift version: 5.2

Paul Hudson @twostraws May 28th 2019

If you’re showing sensitive data it can be important to know when you’re user takes a screenshot. Snapchat, for example, automatically notifies participants in a conversation if someone takes a screenshot, effectively letting them know their privacy might have been breached.

The key is to watch for the .UIApplicationUserDidTakeScreenshot message to be posted, which will happen whenever a screenshot happens. For example, this runs a screenshotTaken() method:

NotificationCenter.default.addObserver(self, selector: #selector(screenshotTaken), name: UIApplication.userDidTakeScreenshotNotification, object: nil)

And this just prints a log message instead:

NotificationCenter.default.addObserver(forName: UIApplication.userDidTakeScreenshotNotification, object: nil, queue: OperationQueue.main) { notification in
    print("Screenshot taken!")
}

Use whichever of those two fits your needs best.