title: Xcode-beta 8. Can't create core data
body: <p>I have been trying to add core data.
  And every time I got the same error: </p>
  
  <pre><code>error: filename "EntityName +CoreDataClass.swift" used twice: '/Users/userName/Desktop/Development/MyApp/AppName/EntityName +CoreDataClass.swift' and '/Users/userName/Library/Developer/Xcode/DerivedData/AppName-dgwzrmxsetzvtedibxrazuutjwnh/Build/Intermediates/AppName.build/Debug-iphoneos/AppName.build/DerivedSources/CoreDataGenerated/Model/EntityName +CoreDataClass.swift'
  </code></pre>
  
  <p>I add core data using the following steps:<br>
  1.New file/ DataModel; save it in the root dir of my project<br>
  select Model.xcdatamodeld and add entity, add several attributes, save,
  editor/create NSManagedObjectClass Subclass.</p>
  
  <p>As a result I observe 4 new files in navigator:
  Model.xcdatamodeld, EntityName+CoreDataProperties.swift, EntityName +CoreDataClass.swift, <strong>_COREDATA_DATAMODELNAME_</strong>+CoreDataModel.swift</p>
  
  <p>their content:
  <strong>_COREDATA_DATAMODELNAME_</strong>+CoreDataModel.swift:  </p>
  
  <pre><code>import Foundation
  import CoreData
  
  ___COREDATA_DATAMODEL_MANAGEDOBJECTCLASSES_IMPLEMENTATIONS___
  </code></pre>
  
  <p>EntityName +CoreDataClass.swift:  </p>
  
  <pre><code>import Foundation
  import CoreData
  
  
  class EntityName: NSManagedObject {
  
  }
  </code></pre>
  
  <p>EntityName+CoreDataProperties.swift:  </p>
  
  <pre><code>import Foundation
  import CoreData
  
  extension EntityName {
  
      @nonobjc class func fetchRequest() -&gt; NSFetchRequest&lt; EntityName &gt; {
          return NSFetchRequest&lt; EntityName &gt;(entityName: "EntityName");
      }
  
      @NSManaged var str: String?
  
  }
  </code></pre>
  
  <p>What I have tried:<br>
  1. Clean build, remove DerivedData, delete content of var/folders, restart<br>
  2. Delete generated files, displayed in navigator</p>
  
  <p>All my efforts were out of luck.<br>
  What I am doing wrong?</p>