#region Namespaces

using 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;

#endregion

namespace DeleteObject

{

    [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)

        {

            UIApplication revit = commandData.Application;

            ElementSet collection = revit.ActiveUIDocument.Selection.Elements;

            if (collection.Size < 1)

            {

                message = "Plase select object(s) before delete.";

                return Result.Cancelled;

            }

            bool error = true;

            try

            {

                error = true;

                IEnumerator e = collection.GetEnumerator();

                Transaction transactoin = new Transaction(commandData.Application.ActiveUIDocument.Document, "DeleteObject");

                transactoin.Start();

                bool MoreValue = e.MoveNext();

                while (MoreValue)

                {

                    Element component = e.Current as Element;

                    revit.ActiveUIDocument.Document.Delete(component.Id);

                    MoreValue = e.MoveNext();

                }

                transactoin.Commit();

                error = false;

            }

            catch (Exception)

            {

                foreach (Element c in collection)

                {

                    elements.Insert(c);

                }

                message = "object(s) can't be deleted.";

                return Result.Failed;

            }

            finally

            {

                if (error)

                {

                    TaskDialog.Show("Error", "Delete failed.");

                }

            }

            return Result.Succeeded;

        }

    }

}