How do I update the UI from a HttpWebRequest? - silverlight

Question

In my Mainpage.xaml.cs file I have a function that creates an instance of another class and tries to download a webpage using a HttpWebRequest from that instance. The problem is, once I've managed to download the webpage I can't send it back to the main UI thread. I've tried using Deployment.Current.Dispatcher.BeginInvoke to send the webpage back to a TextBlock I have waiting, but when I try I get an error telling me that I can't access the TextBlock from the other class. Is there any way to pass data between two threads without using LocalStorage?
EDIT: code below:
MainPage:
private void button1_Click(object sender, RoutedEventArgs e)
{
Member m = new Member(name, id);
}
Member class:
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

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