This class is the abstract base class for all Core Data persistent stores. Core Data provides four store types—SQLite, Binary, XML, and In-Memory (the XML store is not available on iOS); these are described in Persistent Store Features. Core Data also provides subclasses of NSPersistentStore that you can use to define your own store types: NSAtomicStore and NSIncrementalStore.Available in iOS 3.0, OS X v10.5 and later.