Iterate through a Collection Object

acObjId = acLyrTbl["MyLayer"];




using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;

[CommandMethod("IterateLayers")]
public static void IterateLayers()
{
  // Get the current document and database, and start a transaction
  Document acDoc = Application.DocumentManager.MdiActiveDocument;
  Database acCurDb = acDoc.Database;

  using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
  {
      // This example returns the layer table for the current database
      //현재 데이터베이스 레이어 테이블을 반환
      LayerTable acLyrTbl;
      acLyrTbl = acTrans.GetObject(acCurDb.LayerTableId,
                                   OpenMode.ForRead) as LayerTable;

      // Step through the Layer table and print each layer name
      //레이어 테이블을 통해 단계와 각 레이어의 이름을 인쇄
      foreach (ObjectId acObjId in acLyrTbl)
      {
          LayerTableRecord acLyrTblRec;
          acLyrTblRec = acTrans.GetObject(acObjId,
                                          OpenMode.ForRead) as LayerTableRecord;

          acDoc.Editor.WriteMessage("\n" + acLyrTblRec.Name);
      }

      // Dispose of the transaction
  }
}

LayerTable 개체에 MyLayer라는 레이어 테이블 레코드 찾기
다음 예제는 MyLayer라는 레이어가 존재하거나하지 않을 경우 결정 LayerTable 개체를확인하고, 적절한 메시지를 표시합니다



using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;


[CommandMethod("FindMyLayer")]
public static void FindMyLayer()
{
  // Get the current document and database, and start a transaction
  Document acDoc = Application.DocumentManager.MdiActiveDocument;
  Database acCurDb = acDoc.Database;


  using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
  {
      // Returns the layer table for the current database
      LayerTable acLyrTbl;
      acLyrTbl = acTrans.GetObject(acCurDb.LayerTableId,
                                   OpenMode.ForRead) as LayerTable;


      // Check to see if MyLayer exists in the Layer table
      //MyLayer는 레이어 테이블에 존재하는지 확인
      if (acLyrTbl.Has("MyLayer") != true)
      {
          acDoc.Editor.WriteMessage("\n'MyLayer' does not exist");
      }
      else
      {
          acDoc.Editor.WriteMessage("\n'MyLayer' exists");
      }


      // Dispose of the transaction
  }
}

출처
http://docs.autodesk.com/ACD/2010/ENU/AutoCAD%20.NET%20Developer%27s%20Guide/index.html