# Configuring Attributes Describe the properties that compose an entity. ## Discussion After you create an entity as described in [Configuring Entities](/documentation/CoreData/configuring-entities), you can add attributes to that entity. An attribute describes a property of an entity. At minimum, you need to specify the property’s name and data type, whether it must be saved in the store, and whether it’s required to have a value when it’s saved. For some attribute types, you can also choose whether to use a scalar type to represent the attribute in generated classes, as well as configure the attribute to have a default value, or to apply data validation rules. ### Add Attributes Add an attribute as indicated in the screenshot and the steps that follow:  1. With an entity selected, click Add Attribute at the bottom of the editor area. A new attribute with the placeholder name `attribute`, of type `Undefined`, appears in the Attributes list. 2. In the Attributes list, double-click the newly added attribute, and rename it. 3. In the Attributes list, as shown in the second screenshot, click `Undefined` and choose the attribute’s data type from the Type pop-up menu.  ### Configure Attributes Use the data model inspector (choose View > Inspectors > Show Data Model Inspector) to configure attributes.  - Attribute Type: The attribute’s data type. This field reflects the selection made in the Attributes list’s Type pop-up menu. For the full list of types, see [`NSAttributeType`](/documentation/CoreData/NSAttributeType). - Optional: Optional attributes aren’t required to have a value when saved to the persistent store. Attributes are optional by default. Core Data optionals aren’t the same as Swift optionals. You can use a Swift optional to represent a required attribute, for example, if you need flexibility to set its value during the time between the object’s initialization and its first save. - Transient: Transient attributes aren’t saved to the persistent store. By default, attributes are saved to the store. Transient attributes are a useful place to temporarily store calculated or derived values. Core Data does track changes to transient property values for undo purposes. - Allows Cloud Encryption: For persistent stores that write to a CloudKit database, this option instructs the system to encrypt the attribute’s value before it’s sent to iCloud. For more information, see [`allowsCloudEncryption`](/documentation/CoreData/NSAttributeDescription/allowsCloudEncryption). - Default Value: Most types allow you to supply a default value. New object instances set the attribute to this default value on initialization, unless you specify another value at that time. Supplying a default value, in combination with making the type non-optional, can provide performance benefits. - Use Scalar Type: Optionally, for some types, choose between scalar and nonscalar representations during code generation. For a `Double`, selecting the Use Scalar checkbox produces a , while leaving it unselected produces an . For the full list of types, including scalar variants, see [`NSAttributeType`](/documentation/CoreData/NSAttributeType). - Validation: Optionally, set validation rules, such as the minimum and maximum values for a numeric type, or regular expressions requirements for strings. The data model inspector shows validation options specific to the selected attribute’s type. - Index in Spotlight: Adds the field to the Spotlight index for instances created from this entity. For more information, see . - Preserve After Deletion: Includes the attribute in this entity’s tombstone. When persistent history tracking is enabled and a context deletes a managed object, Core Data records an identifying marker, known as its tombstone, in the relevant transaction. - User Info: A dictionary in which you can store any application-specific information related to the attribute. - Versioning Hash Modifier: Provide a hash modifier when maintaining multiple model versions if the structure of an attribute is the same, but the format or content of its data has changed. - Versioning Renaming ID: If you rename an attribute between model versions, set the renaming identifier in the new model to the name of the corresponding attribute in the previous model. For more information, see [Migrating your data model automatically](/documentation/CoreData/migrating-your-data-model-automatically). --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)