iOS wkwebview获取自定义UA

  //获取自定义ua
        self.webView.evaluateJavaScript("navigator.userAgent", completionHandler: { (obj: Any?, error: Error?) in
           guard let ua = obj as? String else {
                return
            }
            let customUA = "\(ua)isapp"
            UserDefaults.standard.register(defaults: ["UserAgent": customUA])
            UserDefaults.standard.synchronize()
            debugPrint("navigator.userAgent\(customUA)")
            //不添加以下代码则只是在本地更改UA，网页并未同步更改
            self.webView.setValue(customUA, forKey: "applicationNameForUserAgent")
        })

重点在于：self.webView.setValue(customUA, forKey: "applicationNameForUserAgent") 这句才能生效