# Returns the persistent store coordinator for the application.  This
  # implementation will create and return a coordinator, having added the
  # store for the application to it.  (The folder for the store is created,
  # if necessary.)
  def persistentStoreCoordinator
    if @persistentStoreCoordinator
      return @persistentStoreCoordinator
    end

    error = Pointer.new_with_type('@')

    fileManager = NSFileManager.defaultManager
    applicationSupportFolder = self.applicationSupportFolder

    if !fileManager.fileExistsAtPath(applicationSupportFolder, isDirectory:nil)
      fileManager.createDirectoryAtPath(applicationSupportFolder, attributes:nil)
    end

    url = NSURL.fileURLWithPath(applicationSupportFolder.stringByAppendingPathComponent("Grokking Recipes.xml"))
    options = { NSMigratePersistentStoresAutomatically: NSNumber.numberWithBool(true)}
    @persistentStoreCoordinator = NSPersistentStoreCoordinator.alloc.initWithManagedObjectModel(self.managedObjectModel)
    if !@persistentStoreCoordinator.addPersistentStoreWithType(NSXMLStoreType, configuration:nil, URL:url, options:options, error:error)
      NSApplication.sharedApplication.presentError(error[0])
    end

    return @persistentStoreCoordinator
  end