ItemContainerGenerator.ContainerFromIndex Method

Parameters

• index
  Type: System.Int32
  The index of the item to retrieve.

Return Value

Type: System.Windows.DependencyObject
The container for the item at the specified index within the item collection, if the item has a container; otherwise, nulla null reference (Nothing in Visual Basic).

Public Sub New()
    InitializeComponent()
    Dim myItems As String() = New String() {"Item 1", "Item 2", "Item 3", "Item 4", "Item 5"}
    myTreeView.DataContext = myItems
End Sub
Shared count As Integer = 1
Private Sub Button_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
    Dim item As TreeViewItem = DirectCast(myTreeView.ItemContainerGenerator.ContainerFromIndex(3), TreeViewItem)
    item.IsExpanded = True
    If count < 5 Then
        item.Items.Add("Child " & count.ToString())
        count += 1
    End If
End Sub

public MainPage()
{
    InitializeComponent();
    string[] myItems = new string[]{"Item 1", "Item 2", "Item 3", "Item 4", "Item 5"};
    myTreeView.DataContext = myItems;
}
static int count = 1;
private void Button_Click(object sender, RoutedEventArgs e)
{
    TreeViewItem item = (TreeViewItem)myTreeView.ItemContainerGenerator.ContainerFromIndex(3);
    item.IsExpanded = true;
    if (count < 5)
    {
        item.Items.Add("Child " + count.ToString());
        count++;
    }
}

<StackPanel x:Name="LayoutRoot" Background="White">
    <sdk:TreeView x:Name="myTreeView" Width="200" ItemsSource="{Binding}" Margin="5"/>
    <Button Content="Add Child to Item 4" Width="150" Click="Button_Click"/>
</StackPanel>