Core Data in Objective-C, 3rd Edition

Persistent Store Types

Four types of repositories are included with the Core Data API: SQLite, XML, binary, and in-memory. (XML is available only on OS X, not on iOS.) In-memory is technically not a persistent store because it is never written out to disk. Binary is effectively a serialized version of the object graph written out to disk. The XML store writes out the object graph to a human-readable text file, and SQLite stores the object graph in a relational database. When you’re working with an iOS project, it’s common to just use SQLite unless there’s a specific reason to use one of the other store formats.

Atomic Stores

Atomic stores include XML, binary, and custom data stores. All of these stores are written to disk atomically; in other ...