Core Data for iOS: Developing Data-Driven Applications for the iPad, iPhone, and iPod touch

Chapter 7. Working with Predicates

IN THIS CHAPTER

• Predicate Basics

• Comparing Strings

• Compound Predicates

• Sets and Relationships

• Examining SQL Queries

• Adding a Search Display Controller

Although predicates are not unique to the Core Data framework, they are such key ingredients to fetch requests that it’s important to have a thorough understanding of predicate syntax. Predicates are the way you specify constraints on what is returned from a fetch request. If you don’t use a predicate, all the objects for a specified entity will be returned.

This chapter begins with the basics of creating an NSPredicate, discussing simple predicate format strings. You’ll learn how to use predicates to match against scalar values like numbers or dates, ...