treeview判断节点是不是已存在

/// <summary>
        /// 判断treeView的节点是否已存在  treeView1.Nodes[0].Nodes
        /// </summary>
        /// <param name="text"></param>
        /// <returns></returns>
        private bool NodeExists(string text)
        {
            TreeNodeCollection treeNodes = treeView1.Nodes[0].Nodes;
            bool exist = false;
            foreach (TreeNode node in treeNodes)
            {
                if (node.Text == text)
                {
                    exist = true;
                    break;
                }
            }
            return exist;
        }

private void toolStripButton新建_Click(object sender, EventArgs e)
        {
            //新建
            ViewForm f = new ViewForm();
            f.Text = "新建";
            if (DialogResult.OK == f.ShowDialog())
            {
                string s = f.textBox1.Text;
                if (!NodeExists(s))
                {
                    treeView1.Nodes[0].Nodes.Add(s);
                }
                else
                {
                    MessageBox.Show("当前节点已经存在，请换个名字。","提示",MessageBoxButtons.OK,MessageBoxIcon.Information);
                }
            }
        }