本例只要演示Revit的类过滤器的用法，在对话框中显示DesignOption元素。

#region Namespacesusing System;using System.Collections;using System.Collections.Generic;using System.Diagnostics;using Autodesk.Revit.ApplicationServices;using Autodesk.Revit.Attributes;using Autodesk.Revit.DB;using Autodesk.Revit.UI;using Autodesk.Revit.UI.Selection;#endregionnamespace DesignOptionReader{    [Autodesk.Revit.Attributes.Transaction(TransactionMode.Manual)]    [Autodesk.Revit.Attributes.Regeneration(RegenerationOption.Manual)]    [Autodesk.Revit.Attributes.Journaling(JournalingMode.NoCommandData)]    public class Command : IExternalCommand    {        public Result Execute(          ExternalCommandData commandData,          ref string message,          ElementSet elements)        {            try            {                Application application = commandData.Application.Application;                ElementClassFilter filter = new ElementClassFilter(typeof(Autodesk.Revit.DB.DesignOption));                FilteredElementCollector collector = new FilteredElementCollector(commandData.Application.ActiveUIDocument.Document);                collector.WherePasses(filter);                IEnumerator iter = collector.GetElementIdIterator();                Element element;                ElementSet designOptions = new ElementSet();                while (iter.MoveNext())                {                    element = iter.Current as Element;                    if (element.GetType().Equals(typeof(Autodesk.Revit.DB.DesignOption)))                    {                        designOptions.Insert(element);                    }                }                if (designOptions.Size > 0)                {                    DesignOptionsDialog dialog = new DesignOptionsDialog();                    foreach (Element elem in designOptions)                    {                        dialog.DesignOptionsList.Items.Add(elem.Name);                                  }                    dialog.ShowDialog();                }                else                {                    TaskDialog.Show("DesignOptions","There are no design options in this document");                }                            }            catch (Exception ex)            {                message = ex.Message;                return Result.Failed;            }            return Result.Succeeded;        }    }}