Core Data for iOS: Developing Data-Driven Applications for the iPad, iPhone, and iPod touch

Chapter 8. Migration and Versioning

IN THIS CHAPTER

• The Migration Problem

• Multiple Data Model Versions and Lightweight Migration

• Renaming Entities and Attributes

• Mapping Models

• Custom Entity Migration Policies

When using the code provided by Apple in the Core Data project templates at the time of writing, a Core Data-based iOS application will only be able to work with a persistent store created using the current data model version. During the development of an application, you typically go through several different revisions of the data model. If you make a change to the data model, such as adding a new attribute on an entity, the Core Data framework will raise an exception and refuse to load the persisted data.

In order to support ...