Versioning and Migrating Data

  • Michael Privat
  • Rob Warner

Abstract

As you develop Core Data-based applications, you usually don’t get your data model exactly right the first time. You start by creating a data model that seems to meet your application’s data needs, but as you progress through the development of the application, you’ll often find that your data model should change to serve your growing vision of what your application will do. During this stage of your application’s life, changing your data model to match your new understanding of the application’s data poses little cost: your application will no longer launch, crashing on startup with the message:

The model used to open the store is incompatible with the one used to create the store

You resolve this issue either by finding the database file on the file system and deleting it or by deleting your fledgling application from the iPhone Simulator or your device. Either way, the database file that uses your outdated schema disappears, along with data in the persistent store, and your application re-creates the database file the next time it launches. You’ll probably do this several times during the development of your application.

Keywords

Migration Detritus 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

Copyright information

© Michael Privat and Rob Warner 2011

Authors and Affiliations

  • Michael Privat
  • Rob Warner

There are no affiliations available

Personalised recommendations