通过js来判断Retina屏幕
首先,给普通的分辨率引入320*460的图片:

的<link rel="apple-touch-start-image" href="start.png"media="screen (max-device-weidth:320px)" />视网膜屏幕JS:
((app.device.type ===“iPhone”| | app.device.type ===的“iPod”)&& app.device.version> = '5'&& window.devicePixelRatio> = 2){$( “头”)。追加($('<link rel="apple-touch-startup-image" href="start-640-920.png" />'));}