Question

In my windows phone application I am using singleton classes for sending and receiving web request and response. So in my current implementation I will call the web request from viewmodel along with an Action<> delegate. For retrieving error call back and it is working fine for me. My issue is that when I fast app switch the application, the web request cancels and it returns a web error. I need to get this web exception in my view model. How can I get this response by using the Func<> delegate? Please anyone help me to solve this issue.

// viewmodel code
private void Login()
{
    LoginContoller.Instance.Login(userName, password, ErrorCallbackCompleted);
}
//callback
private void ErrorCallbackCompleted()
{

}

// code inside singleton class
public static Action ErrorCallbackResponse;

public void Login (string userName, string password, Action errorCallback)
{
    ErrorCallbackResponse = errorCallback;
}

// This method will be invoked from the error callback of web request class
public void GetErrorCallBack(Exception ex) 
{
    ErrorCallbackResponse();
    //I need to pass this ex object to  my viewmodel using Func<>
}

Answer 1

// viewmodel code
  private void Login()
  {
       LoginContoller.Instance.Login(userName, password, ErrorCallbackCompleted);
  }

 //callback
 public void ErrorCallbackCompleted(Exception exception)
 {
 }

// code inside singleton class

  public static Action<Exception> ErrorCallbackResponse;

public void Login (string userName, string password, Action<Exception> errorCallback)
{
   ErrorCallbackResponse = errorCallback;
}

public void GetErrorCallBack(Exception ex) // This method will be invoked from the error callback of web request class
{
    ErrorCallbackResponse(ex);
}