https://blog.wongcw.com/2018/11/30/ios-12%e6%9b%b4%e6%96%b0%e7%8e%87%e5%b7%b2%e8%b6%8575%ef%bc%9a%e6%af%94ios-11%e6%8f%90%e5%89%8d%e4%b8%89%e9%80%b1/