当我使用iframe时，DidFinishNavigation永远不会被调用

Question

我试图在 WKWebView 中加载一些网页。我想在加载webview时在屏幕上显示加载微调器，并在页面加载后隐藏它（特别是当 DidFinishNavigation 被调用时），但 DidFinishNavigation 永远不会被调用正在加载的页面包含HTML中的iframe元素，因此，我无法隐藏加载微调器。

请让我知道为什么会发生这种情况，以及是否有解决此问题的方法。

例如：

网络代码

<section id="Document">
    <iframe  src="SomeOtherPages"></iframe>
    <div id="Loader"></div>
</section>

XAMARIN代码

  public override void ViewDidLoad()
        {
            base.ViewDidLoad();

            var userController = new WKUserContentController();

            // add JS function to the document so we can call it from C#
            userController.AddUserScript(
                new WKUserScript(
                    new NSString(Global.MessageHandlerFunction),
                    WKUserScriptInjectionTime.AtDocumentEnd, false));

            // register messageHandler 'native' that can be called with window.webkit.messageHandlers.native
            userController.AddScriptMessageHandler(this, "native");

            var config = new WKWebViewConfiguration { UserContentController = userController };

            webView = new WKWebView(View.Frame, config) { WeakNavigationDelegate = this };
            webView.AllowsBackForwardNavigationGestures = true;
            webView.UIDelegate = this;
            webView.NavigationDelegate = this;

            View.AddSubview(webView);
            this.loadingOverlay = new LoadingOverlay(View.Frame);
            View.AddSubview(loadingOverlay);

            webView.LoadRequest(new NSUrlRequest(new NSUrl(defaultUrl)));
        }

        [Export("webView:decidePolicyForNavigationAction:decisionHandler:")]
        public void DecidePolicy(WKWebView webView, WKNavigationAction navigationAction, Action<WKNavigationActionPolicy> decisionHandler)
        {
            decisionHandler(WKNavigationActionPolicy.Allow);
            Console.WriteLine("DecidePolicy " + webView.Url);
            SetLoadingOverlay(false);    
        }

        public void SetLoadingOverlay(bool hide){
            InvokeOnMainThread(()=>{
                UIView.Animate(0.5, () => { loadingOverlay.Hidden = hide; });
            });
        }

        [Export("webView:didFinishNavigation:")]
        public void DidFinishNavigation(WKWebView webView, WKNavigation navigation)
        {
            Console.WriteLine("Finish Loading...");
            SetLoadingOverlay(true);
        }

        [Export("webView:didFailNavigation:withError:")]
        public void DidFailNavigation(WKWebView webView, WKNavigation navigation, NSError error)
        {
            Console.WriteLine("Failed Loading...");
            SetLoadingOverlay(true);
        }

        [Export("webView:didFailProvisionalNavigation:withError:")]
        public void DidFailProvisionalNavigation(WKWebView webView, WKNavigation navigation, NSError error)
        {
            Console.WriteLine("Failed Loading...");
            SetLoadingOverlay(true);
        }