Đặt tên cho mối quan hệ, chọn các điểm đến là các thực thể luận. Chọn một mối quan hệ To-Nhiều (có nghĩa là người sử dụng sẽ có nhiều ý kiến ) và làm cho Cascade quy tắc xóa theo cách này, tất cả các ý kiến thuộc về một người sử dụng sẽ được xóa khi người dùng đã được xóa. | Core Data 523 o 0 New File New Data Model File r Cancel Previous Next Figure Naming the data model. Add Entity Add Attribute Add Fetched Property Add Relationship Add Fetch Request Copy Method Declarations to Clipboard Copy Method Implementations to Clipboard Copy Obj-C Method Declarations to Clipboard Copy Obj-C Method Implementations to Clipboard Cut Copy Paste Bring to Front Send to Back Alignment Size Figure Adding a new entity to the model. 524 iPhone SDK 3 Programming Figure Configuring the new User entity. Figure Adding a new attribute to the User entity. 9. Name the relationship comments pick the destination to be the Comment entity. Choose a To-Many relationship meaning the user will have many comments and make the delete rule Cascade this way all comments that belong to a user will be deleted when that user is deleted. See Figure . 10. Select the Comment entity and add a relationship as shown in Figure . Notice that we choose the inverse to be comments and the delete rule to be No Action. The resulting model diagram is shown in Figure . Core Data 525 Figure Specifying the parameters for the name attribute of the User entity. Figure The User entity with three attributes. Figure Adding a relationship in the User .
