Core Data model

Overview

In most cases, you describe your app’s data model using Xcode’s data model editor. NSManagedObjectModel represents the .xcdatamodeld file in your project’s source list. This is where you define entities that you use to generate NSManagedObject subclasses for Core Data to manage.

The entities you create are NSEntityDescription instances. Entities’ properties are subclasses of NSPropertyDescription, namely NSAttributeDescription for attributes, NSRelationshipDescription for relationships, and NSFetchedPropertyDescription for fetched properties.

The various attribute types are enumerated in NSAttributeType.

Topics

Objects and entities

• NSManagedObject
• NSEntityDescription

Standard attributes

• NSPropertyDescription
• NSAttributeDescription
• NSAttributeType
• NSRelationshipDescription

Computed attributes

• NSCompositeAttributeDescription
• NSDerivedAttributeDescription

Fetched properties

• NSFetchedPropertyDescription

See Also

Data modeling

• Modeling data