Chapter 12. Reading and writing application data


This chapter covers
  • Core Data basics
  • Data models
  • The NSFetchedResultsController class
  • Data validation and performance


How useful would the Contacts application be if all your contacts were gone when you quit the application? Or how useful would the Notes application be if all your notes were lost when you turned off your iPhone? Not very useful at all. What is the one thing that makes these and most other applications useful? It’s data persistence: the permanent storage of data that “survives” the closing of an application or even the restart or shutdown of the device.

Data persistence is needed in almost every application in one way or another. In a game, you might need to save high ...

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