With the introduction of iCloud, Apple introduced a new API called UIDocument. UIDocument is designed to be an abstract parent class that makes it easy to integrate applications with iCloud. One of the Core Data API changes for iOS 6.0 is UIManagedDocument, a subclass of UIDocument.
Fundamentally, the biggest advantage of using UIManagedDocument is the ability to abstract away the saving and state of your Core Data stack. With UIManagedDocument, saving is handled automatically and generally occurs asynchronously. You can request saves to occur more frequently than the autosave handles, but in general you shouldn’t need to do that. In addition to managing the saving of the Core Data stack, UIManagedDocument