generic findOrCreate function for NSManagedObjects with an id

gistfile1.swift

  private func findOrCreate<T:NSManagedObject>( managedObjType:T.Type, id: NSNumber ) -> T {
    
    let className = toString(T).pathExtension
    let fetchRequest = NSFetchRequest(entityName: className)
    fetchRequest.predicate = NSPredicate(format: "id == %@", id )
    let foundManagedObjects = self.managedObjectContext?.executeFetchRequest(fetchRequest, error: nil) as? [T]
    let managedObject = (foundManagedObjects == nil || foundManagedObjects!.isEmpty)
      ? NSEntityDescription.insertNewObjectForEntityForName(className, inManagedObjectContext: self.managedObjectContext!) as? T
      : foundManagedObjects!.first
    
    return managedObject!
    
  }