Anyone who has never made a mistake has never tried anything new.
In Chapter 2 the basics of managed object models were introduced, yet you were constrained to just one entity and a few attributes. The next logical step is to add more to the model, however this requires a number of preliminary steps in order to prevent crashes caused by these changes. This chapter will show how to add model versions, model mappings and also demonstrate different migration techniques you can choose when upgrading a model.
As an application evolves, its managed object model will probably need to change. Simple changes such as attribute defaults, validation rules and fetch request ...