TreeViewItem parentItem = new TreeViewItem(); parentItem.Header = "Parent Node"; TreeViewItem childItem1 = new TreeViewItem(); childItem1.Header = "Child Node 1"; TreeViewItem childItem2 = new TreeViewItem(); childItem2.Header = "Child Node 2"; parentItem.Items.Add(childItem1); parentItem.Items.Add(childItem2); parentItem.ExpandSubtree();
TreeViewItem rootNode = new TreeViewItem(); rootNode.Header = "Root Node"; TreeViewItem childNode = new TreeViewItem(); childNode.Header = "Child Node"; rootNode.Items.Add(childNode); TreeView treeView = new TreeView(); treeView.Items.Add(rootNode); childNode.ExpandSubtree();In this example, a `TreeViewItem` is created as the root node and a child node is added to it. Then, the `TreeView` control is created and the root node is added to it. Finally, the `ExpandSubtree()` method is called on the child node, which expands it.