使用下面的标签可以自定义图标
<link rel=”apple-touch-icon-precomposed” href=”icon.png”>

该标签还支持size属性，可以指定不同尺寸
<link rel=”apple-touch-icon-precomposed” sizes=”57×57″ href=”icon-57.png”>
<link rel=”apple-touch-icon-precomposed” sizes=”72×72″ href=”icon-72.png”>
<link rel=”apple-touch-icon-precomposed” sizes=”114×114″ href=”icon-114.png”>
<link rel=”apple-touch-icon-precomposed” sizes=”144×144″ href=”icon-144.png”>