问题
I want to handle UserFallback to show a pass code screen.
I tried this tutorial, but when my UserFallback is called it will ask for Touch-ID again.
If I use a wrong finger or Touch-ID did fail, then it's showing Apple's default Passcode screen.
Please help me.
来源：https://stackoverflow.com/questions/31891577/how-to-display-iphone-pass-code-screen-when-user-touch-id-authentication-userfa