Core Data in Objective-C, Third Edition

Data Storage and Management for iOS and OS X

Marcus S. Zarra

Core Data expert Marcus Zarra walks you through a fully developed application based around the Core Data APIs. You'll build on this application throughout the book, learning key Core Data principles such as NSPredicate, NSFetchRequest, thread management, and memory management.

Start with the basics of Core Data and learn how to use it to develop your application. Then delve deep into the API details. Explore how to get Core Data integrated into your application properly, and work with this flexible API to create convenience methods to improve your application's maintainability. Reduce your migration difficulties, integrate your Core Data app with
iCloud, and use Core Data in a queue-based environment. By the end of the book, you'll have built a full-featured application, gained a complete understanding of Core Data, and learned how to integrate your application into the iPhone/iPad platform.

This third edition updates all examples for OS X El Capitan and iOS 9, and gets you up to speed on changes in multithreading and batch processing. There's a new chapter on efficiently importing data from a network location, and a new discussion of how best to pre-load data into your application.

Core Data Top Five Tips by Marcus Zarra

• In a multi-threaded environment, always turn on the -com.apple.CoreData.ConcurrencyDebug 1 setting when you are running in debug mode. This will catch threading errors during development.

• Only use one NSManagedObjectContext for your entire User Interface. The User Interface is designed to run on a single thread and therefore using additional NSManagedObjectContext instances is unnecessary and creates problems.

• If you are using the parent/child design with Core Data, do not try and reuse child NSManagedObjectContext instances. They are cheap and meant to be thrown away after a single use.

• Every time you ship your application with a model change, tag that commit in your version control system so that if the model accidentally gets altered you can quickly find the original.

• Every "error" that Core Data can potentially produce is a developer preventable error. If you treat them as hard errors (with a call to abort, for example) you will be able to test for them more easily and your error handling code becomes far less complex.

Table of contents

• Core Data in Objective-C, Third E dition