Graphics Programs Reference
In-Depth Information
Core Data is a very powerful and flexible persistence framework, and this chapter has
been just a quick introduction to its capabilities. For more details, we strongly suggest that
you read Apple's Core Data Programming Guide . Here are some of the things we have
not delved into:
NSFetchRequest is a powerful mechanism for specifying data you want from
the persistent store. We used it a little, but you will want to go deeper. You should
also explore the following related classes: NSPredicate , NSSortOrdering ,
NSExpressionDescription , and NSExpression . Also, fetch request
templates can be created as part of the model file.
• A fetched property is a little like a to-many relationship and a little like an
NSFetchRequest . You typically specify them in the model file.
• As your app evolves from version to version, you'll need to change the data mod-
el over time. This can be tricky - in fact, Apple has an entire book about it: Data
Model Versioning and Data Migration Programming Guide .
• There is good support for validating data as it goes into your instances of
NSManagedObject and again as it moves from your managed object into the
persistent store.
• You can have a single NSManagedObjectContext working with more than
one persistent store. You partition your model into configurations and then assign
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