The recipe object starts as an NSManagedObject for Recipe entity, but then becomes a Pointer without setValue:forKey: support

open_file_selector_and_process.rb

  # Image well
  def addImage(sender)
    return unless recipe = recipeArrayController.selectedObjects.lastObject
    
    p recipe # => #<NSManagedObject_Recipe_:0x800525ee0>
    
    openPanel = NSOpenPanel.openPanel
    openPanel.canChooseDirectories = false
    openPanel.canCreateDirectories = false
    openPanel.allowsMultipleSelection = false
    
    selector = :"addImageSheetDidEnd:returnCode:contextInfo:"
    openPanel.beginSheetForDirectory(nil, file: nil, modalForWindow: window, modalDelegate: self, didEndSelector: selector, contextInfo: recipe)
  end
  
  def addImageSheetDidEnd(openPanel, returnCode: returnCode, contextInfo: recipe)
    return if returnCode == NSCancelButton
    
    guid = NSProcessInfo.processInfo.globallyUniqueString
    destPath = applicationSupportFolder.stringByAppendingPathComponent(guid)
    NSFileManager.defaultManager.copyPath(openPanel.filename, toPath: destPath, handler: nil)
    # recipe.imagePath = destPath # doesn't work?

    p recipe # => #<Pointer:0x80065c1e0>

    recipe.setValue(destPath, forKey:"imagePath")
    # gives error:
    # AppDelegate.rb:154:in `setValue:forKey:': NSUnknownKeyException: [<Pointer 0x80065c1e0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key imagePath. (RuntimeError)
  end