Detect lock button other way.

[songyiYu]

I think it should be better to detect lock screen than lock button. (because of appstore reject issue)
Please review this method.

func applicationProtectedDataDidBecomeAvailable(_ application: UIApplication) {
        print("applicationProtectedDataDidBecomeAvailable")
    }

    func applicationProtectedDataWillBecomeUnavailable(_ application: UIApplication) {
        print("applicationProtectedDataWillBecomeUnavailable")
    }