在 Xamarin IO 中的一个 WebViewRenderer 中实现错误处理和脚本消息接收

Question

现在我有用于Web视图渲染器的代码，如下所示：

 public sealed class MyWebViewRenderer : ViewRenderer<WebView, WKWebView>, IWKScriptMessageHandler
    {
        private const string ScriptMessageHandlerName = "native";
        private WKUserContentController userController;
        private WKWebView m_NativeView;
        protected override void OnElementChanged(ElementChangedEventArgs<WebView> e)
        {
            base.OnElementChanged(e);
            var visualWebView = (ImWebView)Element;
            if (Control == null && e.NewElement != null)
            {
                this.userController = new WKUserContentController();
                var config = new WKWebViewConfiguration
                {
                    UserContentController = this.userController
                };
                this.userController.AddScriptMessageHandler(this, ScriptMessageHandlerName);
                m_NativeView = new WKWebView(this.Frame, config) { WeakNavigationDelegate = new ImNavigationDelegate()};

                SetNativeControl(m_NativeView);
    }
        public void DidReceiveScriptMessage(WKUserContentController userContentController, WKScriptMessage message)
        {
        ...
        }
}

此类允许我从 JS 接收消息。但是现在我想收到页面加载失败的消息。我找到了唯一的方法 - 使用 Xamarin.Forms.Platform.iOS.WebViewRenderer 作为我的渲染器的基类并使用

public sealed class MyWebViewRenderer : Xamarin.Forms.Platform.iOS.WebViewRenderer
 {
    protected override void OnElementChanged(VisualElementChangedEventArgs e)
    {
        base.OnElementChanged(e);
        var visualWebView = (ImWebView)Element;
            if (this.ViewController == null && e.NewElement != null)
            {
                base.Delegate = new CustomNavigationDelegate() { Control = visualWebView };
        }
            ...
     }

    public class CustomNavigationDelegate : UIWebViewDelegate
    {
        public ImWebView Control { get; set; }
        public override void LoadFailed(UIWebView webView, NSError error)
        {
          ...
        }
    }
 }

加载失败捕获运行良好，但是使用此代码，我无法从JS获取消息。有没有办法在一个类中从JS代码中获取LoadFailed事件和消息？

Answer 1

我建议您继续使用从WKWebView继承的渲染器。我们可以在WKNavigationDelegate中使用DidFailNavigation虚拟方法在导航时出错时获取回调。你可以像下面这样使用它

public sealed class MyWebViewRenderer : ViewRenderer<WebView, WKWebView>, IWKScriptMessageHandler
{
    private const string ScriptMessageHandlerName = "native";
    private WKUserContentController userController;
    private WKWebView m_NativeView;
    protected override void OnElementChanged(ElementChangedEventArgs<WebView> e)
    {
        base.OnElementChanged(e);
        var visualWebView = (ImWebView)Element;
        if (Control == null && e.NewElement != null)
        {
            this.userController = new WKUserContentController();
            var config = new WKWebViewConfiguration
            {
                UserContentController = this.userController
            };
            this.userController.AddScriptMessageHandler(this, ScriptMessageHandlerName);
            m_NativeView = new WKWebView(this.Frame, config) { WeakNavigationDelegate = new NavigationDelegate()};

            SetNativeControl(m_NativeView);
        }
    }
        public void DidReceiveScriptMessage(WKUserContentController userContentController, WKScriptMessage message)
        {
        }
}
public class NavigationDelegate : WKNavigationDelegate
{
    public override void DidFailNavigation( WKWebView webView, WKNavigation navigation, NSError error )
    {
        // If navigation fails, this gets called
    }
}