https://blog.wongcw.com/2020/09/16/grayshift%e7%9a%84graykey-iphone%e5%8f%96%e8%ad%89%e5%b7%a5%e5%85%b7%e4%ba%ae%e7%9b%b8%e5%9c%a8fcc%e7%9a%84%e7%85%a7%e7%89%87%e4%b8%ad/