Professional Xcode® 3

Chapter 15. Data Modeling

WHAT'S IN THIS CHAPTER?

• Create a data schema

• Define entities, properties, and relationships

• Migrate between data schema versions

• Quickly create a user interface

Data modeling is a visual tool for defining data objects and their relationships, called a data schema. A schema defines entities that contain properties. Properties can be values or relationships to other entities. The data modeling tools in Xcode let you create and edit a data model, as shown in Figure 15-1. The data model then becomes a resource that can be used by your application at run time.

To use data modeling effectively, you must have a rudimentary understanding of Core Data. If you are not familiar with Core Data, start by perusing the Core Data Programming Guide. You can find it in the Xcode documentation, or you can browse it online at http://developer.apple.com/mac/library/documentation/Cocoa/Conceptual/CoreData/.

This book is not about database development or Core Data programming, but like the chapter on Interface Builder, it's difficult to explain how to use the data modeling tools without describing what you're doing and why. This chapter focuses on the Xcode tools you use to develop and maintain data models. In the process, I'll explain the data model's relationship to the run time environment and touch on some best practices. Just know that the modeling tools are the tip of the Core Data iceberg; Core Data can be extended extensively with custom code — all well beyond the scope of this ...