WPF Update List Box From Another View/Class

Question

Very new to WPF. I am trying to achieve something relatively simple that is proving to be difficult.

Basically, I want to add an Item to my List Box. The List Box is created in my LiveView xaml/class, but I want to update the contents of the List Box when I push a button in my SettingsView Class.

SettingsView class:

public partial class SettingsView : UserControl
   {
       public SettingsView()
           {
               InitializeComponent();
           }

       private void StartButton_Click(object sender, RoutedEventArgs e)
           {
               var myLiveView = new LiveView();
               myLiveView.updateListBox();
           }

}

LiveView class:

public partial class LiveView : UserControl
{
    public LiveView()
    {
        InitializeComponent();
    }

    public void updateListBox()
    {
        CommentListBox.Items.Add("Another item");
    }
}

If I do the following, the code works and an item is sucessfully added to my list on startup.

public partial class LiveView : UserControl
{
    public LiveView()
    {
        InitializeComponent();
        CommentListBox.Items.Add("Another item");
    }
}

Why can I only update the UI inside the Liveview class()? What is the right way to go about this? how can I update my ListBox from another class/view? The instance that I'm creating of LiveView doesn't appear to actually do anything. Any help would be much appreiated, thank you.

Answer 1

Fixed using MVVM which made this whole process much easier.