如何在主窗口中以子级的形式获取当前呈现的UserControl？

Question

I am new to MVVM and using MVVMLight Toolkit. Thus i am working on project where Navigation Take place using based on Uri which is set on Frame exposed on View as x:Name. Here is my Code..

public  virtual void SetFrame(Uri userControll, string FrameElementName)
{
     var mainWindow = Application.Current.MainWindow;
     var frame = mainWindow.FindName(FrameElementName) as Frame;

     if (frame != null)
     {
          frame.Source = userControll;
     }
 }

If we Want navigation function to Work on Currently Rendered UserControll Which is child of MainWindow? What steps we have to perform? Like

public  virtual void SetFrame(Uri anotherUserControll, string FrameElementName)
{
     var userControl= // what to do to get Currently rendered Usercontroll as child of MainWindow?
     var frame = userControl.FindName(FrameElementName) as Frame;

     if (frame != null)
     {
        frame.Source = anotherUserControll;      
     }
 }

Answer 1

I solved this problem by casting Frame.Context as UserControl to get the Current Rendered UserControl.. Here

    public  virtual void SetFrame(Uri anotherUserControll, string FrameElementName)
     {
         var mainFrame =(Frame)Application.Current.MainWindow.FindName("MainFrame");
         var userControll = mainFrame.Content as UserControl;
         var frame = userControll.FindName(contentControll) as Frame;
         if (frame != null)
         {
             frame.Source = anotherUserControll;
         }           
     }