iOS 8 Swift Programming Cookbook

Chapter 17. Core Data

17.0. Introduction

Core Data is a powerful framework on the iOS SDK that allows programmers to store and manage data in an object-oriented way. Traditionally, programmers had to store their data on disk using the archiving capabilities of Objective-C, or write their data to files and manage them manually. With the introduction of Core Data, programmers can simply interact with its object-oriented interface to manage their data efficiently. In this chapter, you learn how to use Core Data to create the model of your application (in the model-view-controller software architecture).

Core Data interacts with a persistent store at a lower level that is not visible to the programmer. iOS decides how the low-level data management is implemented. All the programmer needs to know is the high-level API she is provided with. But understanding the structure of Core Data and how it works internally is very important. Let’s create a Core Data application to understand this a bit better.

With the new LLVM compiler, the only thing you have to do in order to include Core Data into your project is to include the umbrella header file, like so:

import UIKit
import CoreData

To be able to work with Core Data, you need to understand that a Core Data stack is based on the following concepts:

Persistent store

The object that represents the actual database on disk. We never use this object directly.

Persistent store coordinator

The object that coordinates reading and writing of information from ...