Cocoa Programming for OS X: The Big Nerd Ranch Guide

Persistent Store Types

Core Data supports several store types: three for saving and loading data (SQLite, XML, and Binary), and a fourth for caching applications, In-Memory. The Xcode Core Data application template allows the user to choose between the persistence formats in the File Format pop-up button on the save panel.

Which should you use? Each of these types has their strengths, but we recommend SQLite for most applications: it is fast, thanks to its support for incremental updates, and moderately readable – you can open the file in the sqlite3 command-line utility should you need to peek inside the store. The XML format can be inspected too, but it is significantly slower than SQLite.

Note that Core Data is not a database ...