let isIOS = userAgent.toLowerCase().indexOf("like mac os x") > 0; //ios终端
if (isIOS) {
//ios
let regStr_saf = /os [\d._]*/gi;
let verinfo = userAgent.toLowerCase().match(regStr_saf);
var ver = (verinfo + "").replace(/[^0-9|_.]/ig, "").replace(/_/ig, ".");
alert(ver);
}