Prevent iOS from taking screen capture of app before going into background

Question

You all might know that iOS takes a screen shot of your application before throwing it into the background. This is usually for a better User experience like quick animation

Answer 1

Apple Doc https://developer.apple.com/library/archive/qa/qa1838/_index.html

Note: Your implementation of -applicationDidEnterBackground: should not start any animations (pass NO to any animated: parameter). The snapshot of your application's window is captured immediately upon returning from this method. Animations will not complete before the snapshot is taken.

Converted Apple code in swift 4.2 App delegate i declared

func applicationDidEnterBackground(_ application: UIApplication) {
    // Your application can present a full screen modal view controller to
    // cover its contents when it moves into the background. If your
    // application requires a password unlock when it retuns to the
    // foreground, present your lock screen or authentication view controller here.

    let blankViewController = UIViewController()
    blankViewController.view.backgroundColor = UIColor.black

    // Pass NO for the animated parameter. Any animation will not complete
    // before the snapshot is taken.
    window.rootViewController?.present(blankViewController, animated: false)
}

func applicationWillEnterForeground(_ application: UIApplication) {
    // This should be omitted if your application presented a lock screen
    // in -applicationDidEnterBackground:
    window.rootViewController?.dismiss(animated: false) false
}