Core Data in Objective-C, 3rd Edition

Chapter 4Versioning and Migration

Just like a battle plan, no codebase ever survives contact with users. As soon as users start to use an application, they want to change it. Even if the code is just for ourselves, we, also as users, will want to change things. For example, we may need to add an attribute or a new object and then restructure things to accommodate those changes. Additions and changes can be quite involved and invariably require a change in how the data is stored.

Starting with Mac OS X 10.5 Leopard and iOS 3.0, Apple has made data migration nearly trivial for users of Core Data. Taking the project outlined in Chapter 1, ​Building a Foundation​, we’ll add some additional features to it in succeeding versions. Although a data ...