How to Reuse TreeNodeCollection in Windows Forms apps

I’m creating an app and need the same data set for two tree views. Nodes.AddRange only works with a TreeNode[] and the TreeNodeCollection is read-only and doesn’t have a ctor.

I first tried something like this:

TreeNode[] nodes = new TreeNode[treeView1.Nodes.Count];

treeView1.Nodes.CopyTo(nodes,0);

selectForm.treeView1.Nodes.AddRange(nodes);

```python

But got this exception.

> \_Cannot add or insert the item ‘’ in more than one place. You must first remove it from its current location or clone it.
> Parameter name: node\_

Apparently we need to first clone the nodes because they are already bound to the first TreeView.

Here’s the quick and dirty (feel free to make it cleaner w/ extension method, etc)

```csharp

selectForm.treeView1.Nodes.AddRange(TreeViewUtility.CloneNodes(treeView1));
        public static TreeNode[] CloneNodes(TreeView tree)
        {
            TreeNode[] nodes = new TreeNode[tree.Nodes.Count];
            for(int i = 0; i < tree.Nodes.Count; i++)
            {
                nodes[i] = tree.Nodes[i].Clone() as TreeNode;
            }
            return nodes;
        }

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