https://blog.wongcw.com/2021/04/28/%e8%98%8b%e6%9e%9c%e6%9b%be%e8%80%83%e6%85%ae%e8%ae%93ios%e6%94%af%e6%8c%81flash-%e4%bd%86%e6%80%a7%e8%83%bd%e7%b3%9f%e7%b3%95%e9%80%8f%e9%a0%82/