在html的head标签里添加meta
<meta name='viewport' content='width=device-width, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0, user-scalable=no'>
或者手动拼
NSString *headerString = @"<header><meta name='viewport' content='width=device-width, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0, user-scalable=no'></header>";
[strongSelf.contentWebView loadHTMLString:[headerString stringByAppendingString:model.detail] baseURL:nil];