How to Programmatically Expand an Item in WPF TreeViewAdv?

This sample shows how to programmatically expand an item in WPF TreeView (TreeViewAdv).

TreeViewAdv allows to expand or collapse each node by setting IsExpanded property.

XAML

<Grid x:Name="Grid">
    <syncfusion:TreeViewAdv Name="treeViewAdv">
        <syncfusion:TreeViewItemAdv Name="treeViewItemAdv" Header="Marital Status">
            <syncfusion:TreeViewItemAdv Header="Single"/>
            <syncfusion:TreeViewItemAdv Header="Married"/>
            <syncfusion:TreeViewItemAdv Header="Married with Children"/>
        </syncfusion:TreeViewItemAdv>
        <syncfusion:TreeViewItemAdv Header="Baby Vaccines">
            <syncfusion:TreeViewItemAdv Header="Hepatitis B"/>
            <syncfusion:TreeViewItemAdv Header="Tetanus"/>
            <syncfusion:TreeViewItemAdv Header="Polio"/>
            <syncfusion:TreeViewItemAdv Header="Measles"/>
        </syncfusion:TreeViewItemAdv>
        <syncfusion:TreeViewItemAdv Header="Country Information"/>
    </syncfusion:TreeViewAdv>
</Grid>

C#

public MainWindow()
{
    InitializeComponent();
    TreeViewAdv treeViewAdv = new TreeViewAdv();
    TreeViewItemAdv root1 = new TreeViewItemAdv() { Header = "Marital Status" };
    TreeViewItemAdv subitem11 = new TreeViewItemAdv() { Header = "Single" };
    TreeViewItemAdv subitem12 = new TreeViewItemAdv() { Header = "Married" };
    TreeViewItemAdv subitem13 = new TreeViewItemAdv() { Header = "Married with Children" };

    root1.Items.Add(subitem11);
    root1.Items.Add(subitem12);
    root1.Items.Add(subitem13);

    TreeViewItemAdv root2 = new TreeViewItemAdv() { Header = "Baby Vaccines" };
    TreeViewItemAdv subitem21 = new TreeViewItemAdv() { Header = "Hepatitis B" };
    TreeViewItemAdv subitem22 = new TreeViewItemAdv() { Header = "Tetanus" };
    TreeViewItemAdv subitem23 = new TreeViewItemAdv() { Header = "Polio" };
    TreeViewItemAdv subitem24 = new TreeViewItemAdv() { Header = "Measles" };

    root2.Items.Add(subitem21);
    root2.Items.Add(subitem22);
    root2.Items.Add(subitem23);
    root2.Items.Add(subitem24);

    TreeViewItemAdv root3 = new TreeViewItemAdv() { Header = "Baby Vaccines" };
    treeViewAdv.Items.Add(root1);
    treeViewAdv.Items.Add(root2);
    treeViewAdv.Items.Add(root3);
    Grid.Children.Add(treeViewAdv);
    root1.IsExpanded = true;
}

VB

Public Sub New()
    InitializeComponent()
    Dim treeViewAdv As TreeViewAdv = New TreeViewAdv()
    Dim root1 As TreeViewItemAdv = New TreeViewItemAdv() With {.Header = "Marital Status"}
    Dim subitem11 As TreeViewItemAdv = New TreeViewItemAdv() With {.Header = "Single"}
    Dim subitem12 As TreeViewItemAdv = New TreeViewItemAdv() With {.Header = "Married"}
    Dim subitem13 As TreeViewItemAdv = New TreeViewItemAdv() With {.Header = "Married with Children"}

    root1.Items.Add(subitem11)
    root1.Items.Add(subitem12)
    root1.Items.Add(subitem13)

    Dim root2 As TreeViewItemAdv = New TreeViewItemAdv() With {.Header = "Baby Vaccines"}
    Dim subitem21 As TreeViewItemAdv = New TreeViewItemAdv() With {.Header = "Hepatitis B"}
    Dim subitem22 As TreeViewItemAdv = New TreeViewItemAdv() With {.Header = "Tetanus"}
    Dim subitem23 As TreeViewItemAdv = New TreeViewItemAdv() With {.Header = "Polio"}
    Dim subitem24 As TreeViewItemAdv = New TreeViewItemAdv() With {.Header = "Measles"}

    root2.Items.Add(subitem21)
    root2.Items.Add(subitem22)
    root2.Items.Add(subitem23)
    root2.Items.Add(subitem24)

    Dim root3 As TreeViewItemAdv = New TreeViewItemAdv() With {.Header = "Baby Vaccines"}
    treeViewAdv.Items.Add(root1)
    treeViewAdv.Items.Add(root2)
    treeViewAdv.Items.Add(root3)
    Grid.Children.Add(treeViewAdv)
    root1.IsExpanded = True
End Sub