ComboBoxEdit 添加键值

ComboBoxEdit combo = new ComboBoxEdit();
var coll = combo.Properties.Items;
            coll.BeginUpdate();
            try
            {
                var list ；// list集合 
                var item= new ComboBoxItem
                    {
                        Key = "-1",
                        Value = "请选择"
                    };
                    coll.Add(item);
                    coll.AddRange(list);  //批量添加
                    cmb.SelectedIndex = 0;  //默认选择项
            }
            
            finally
            {
                coll.EndUpdate();
            }