如何从 HttpWebRequest 更新 UI？

Question

在我的Mainpage.xaml.cs 文件中，我有一个函数可以创建另一个类的实例并尝试使用该实例中的 HttpWebRequest 下载网页。问题是，一旦我成功下载了网页，我就无法将其发送回主 UI 线程。我尝试使用Deployment.Current.Dispatcher.BeginInvoke 将网页发送回我等待的 TextBlock，但是当我尝试时收到错误消息，告诉我无法从其他类访问 TextBlock。有什么方法可以在不使用 LocalStorage 的情况下在两个线程之间传递数据？

编辑：代码如下：

主页：

private void button1_Click(object sender, RoutedEventArgs e)
    {
        Member m = new Member(name, id);
    }

会员等级：

public Member(String Member, String API)
    {
        APIKey = API;
        MemberName = Member;
        this.super = super;
        DoSend(method, string, "", null);
    }

public void DoSend(string method, string url, string body, string mimetype)
    {
        if (WebRequest.RegisterPrefix("https://",System.Net.Browser.WebRequestCreator.ClientHttp)) {
            HttpWebRequest request = WebRequest.Create(makeURI(url)) as HttpWebRequest;

        request.Method = method;
        request.Headers["X-NFSN-Authentication"] = MakeAuthHeader(url,body);
        if (body != "")
        {
            byte[] bodyData = Encoding.UTF8.GetBytes(body);
            request.ContentType = mimetype;
            //Stuff Should Happen Here
        }

        else
            doStuff(request);
        }

public void doStuff(HttpWebRequest httpReq)
    {
        httpReq.BeginGetResponse(r =>
        {
            var httpRequest = (HttpWebRequest)r.AsyncState;
            var httpResponse = (HttpWebResponse)httpRequest.EndGetResponse(r);

            using (var reader = new StreamReader(httpResponse.GetResponseStream()))
            {
                var response = reader.ReadToEnd();
                ResponseBlock.Text = response; //Invalid cross-thread reference
            }
        }, httpReq);
    }

Answer 1

主页：

customClass.DownloadPage((result) =>
{
    textBlock.Text = result;
},
(exception) =>
{
    MessageBox.Show(exception.Message);
});

自定义类：

public void DownloadPage(Action<string> callback, Action<Exception> exception)
{
    WebClient webClient = new WebClient();
    webClient.DonwloadStringCompleted += (s, e) =>
    {
        if (e.Error == null)
        {
            Deployment.Current.Dispatcher.BeginInvoke(() =>
            {
                callback(e.Result);
            });
        }
        else
        {
            Deployment.Current.Dispatcher.BeginInvoke(() =>
            {
                exception(e.Error);
            });
        }
    };
    webClient.DonwloadStringAsync();
}