bootstrap4示例模板中出现这样的代码

<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">

这行代码的作用可以让网页的宽度自动适应手机屏幕的宽度，但是多了shrink-to-fit=no，

这是什么鬼？查找文档得知，主要是为了兼容iOS9

Viewport meta tags using "width=device-width" cause the page to scale down to fit content that overflows the viewport bounds. You can override this behavior by adding "shrink-to-fit=no" to your meta tag as shown below. The added value will prevent the page from scaling to fit the viewport.