WKWebView检查HTML表单提交

我的任务是将objective-c应用程序转换为fully swift 4。这个应用程序基本上是一个webbroswer,它可以封装我的公司网站。为了让用户每次都抱怨输入了用户名/密码,应用程序需要检查何时提交了html表单,并删除网站并存储u/p。

在objc中有一种方法: - (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType

这让我可以在提交表格时进行检查:

static NSString * const FORM_USER = @"document.getElementById('sUserID').value";
static NSString * const FORM_PASS = @"document.getElementById('sPassword').value";

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType {

        //save form data
        if(navigationType == UIWebViewNavigationTypeFormSubmitted) {
            dispatch_async(dispatch_get_main_queue(), ^{
                //grab the data from the page
                NSString *username = [self.webView stringByEvaluatingJavaScriptFromString: FORM_USER];
                NSString *password = [self.webView stringByEvaluatingJavaScriptFromString: FORM_PASS];

                //store values locally in the background
                //.....
            });

        }
        return true;
    }

但是我很难转换swift 4.1,因为我似乎找不到任何类型的 UIWebViewNavigationTypeFormSubmitted 对于wkwebview。

有什么帮助吗?

let FORM_USER = "document.getElementById('sUserID').value"
let FORM_PASS = "document.getElementById('sPassword').value"

func webView(_ webView: WKWebView, didStartProvisionalNavigation navigation: WKNavigation) {

    if(webView.url == API_LOGIN_URL){

        if(WHAT A DO I CHECK FOR here?){

            //Grab IN LOGIN DETAILS
            var name = webView.evaluateJavaScript("\(FORM_USER)", completionHandler: nil)
            var pass = webView.evaluateJavaScript("\(FORM_PASS)", completionHandler: nil)

            //store values locally
            //...
        }

    }
}