现在IOS新版里是支持退出全屏的，但是我发现，我使用chimee的退出全屏无法使用，是没有做兼容

[DanPlayer]

var elem = this.player.$video || document; if (elem.cancelFullScreen) { elem.cancelFullScreen(); } else if (elem.mozCancelFullScreen) { elem.mozCancelFullScreen(); } else if (elem.webkitCancelFullScreen) { elem.webkitCancelFullScreen(); } else if (elem.webkitExitFullScreen) { elem.webkitExitFullScreen() }