Xamarin.Forms.WebView -获取显示页面的标题？

Question

是否可以在WebView中显示的网页上获取信息？

Answer 1

使用WebView自定义呈现器(https://developer.xamarin.com/guides/cross-platform/xamarin-forms/custom-renderer/)：

public class TitleWebView : Xamarin.Forms.WebView
{
    public static readonly BindableProperty PageTitleProperty = BindableProperty.Create<TitleWebView, string>(v => v.PageTitle, null, BindingMode.OneWayToSource);

    public string PageTitle
    {
        get { return (string)GetValue(PageTitleProperty); }
        set { SetValue (PageTitleProperty, value); } 
    }
}

Android渲染器：

public class TitleWebViewRenderer : WebViewRenderer
{
    protected override void OnElementChanged(ElementChangedEventArgs<Xamarin.Forms.WebView> e)
    {
        base.OnElementChanged(e);

        if (e.OldElement == null)
        {
            Control.SetWebViewClient(new TitleWebViewClient(this));
        }
    }

    internal class TitleWebViewClient : WebViewClient
    {
        readonly TitleWebViewRenderer titleWebViewRenderer;

        internal TitleWebViewClient(TitleWebViewRenderer titleWebViewRenderer)
        {
            this.titleWebViewRenderer = titleWebViewRenderer;
        }

        public override void OnPageFinished(Android.Webkit.WebView view, string url)
        {
            base.OnPageFinished(view, url);
            ((IElementController) titleWebViewRenderer.Element).SetValueFromRenderer(TitleWebView.PageTitleProperty, view.Title);
        }
    }

iOS渲染器：

public class TitleWebViewRenderer : WebViewRenderer
{
    public TitleWebViewRenderer()
    {
        this.LoadFinished += (object sender, EventArgs e) => {
            var titleWebView = (TitleWebView)Element;
            ((IElementController)Element).SetValueFromRenderer(TitleWebView.PageTitleProperty, 
                EvaluateJavascript("document.title"));
        };
    }
}

Answer 2

Daniel Luberda的TitleWebView类解决方案修正了Xamarin 4.2：

    public class TitleWebView : WebView
    {
        public static readonly BindableProperty PageTitleProperty = BindableProperty.Create(
            propertyName: "PageTitle",
            defaultValue: string.Empty,
            returnType: typeof(string),
            declaringType: typeof(string),
            defaultBindingMode: BindingMode.OneWayToSource);

        public string PageTitle
        {
            get => (string) GetValue(PageTitleProperty);
            set => SetValue(PageTitleProperty, value);
        }
    }