Chapter 1, Taking the First Steps with Swift, introduces the reader to the Swift programming language and discusses what inspired Apple to create Swift. We also go over the basic syntax of Swift and how to use Playgrounds to experiment and test Swift code.

Chapter 2, Learning about Variables, Constants, Strings, and Operators, explains to the reader about variables and constants in Swift and when to use them. There are brief overviews of the most common variable types, with examples of how to use them. We conclude this chapter by showing examples of how to use the most common operators in the Swift language.

Chapter 3, Using Collections and Cocoa Data Types, introduces Swift's Array and Dictionary collection types and shows examples of how to use them. We will also show how to use the Cocoa and Foundation data types with Swift.

Chapter 4, Control Flow and Functions, explains how to use Swift's control flow statements. These include looping, conditional, and control transfer statements. The second half of the chapter is all about functions and how to define and use them.

Chapter 5, Classes and Structures, explains Swift's classes and structures in detail. We will look at what makes them similar and what makes them different. We will also look at access controls and object-oriented design. We will close this chapter out by looking at memory management in Swift.

Chapter 6, Working with XML and JSON Data, starts off by discussing what XML and JSON data is and their uses. We then show several examples of how to parse and build XML and JSON data using Apple's frameworks.

Chapter 7, Custom Subscripting, examines how we can use custom subscripts in our classes, structures, and enumerations. Subscripts in Swift can be used to access elements in a collection. We can also define custom subscripts for our classes, structures, and enumerations.

Chapter 8, Using Optional Type and Optional Chaining, looks at what optional types really are, various ways to unwrap them, and optional chaining. For a developer just learning Swift, optional types can be one of the most confusing items to learn.

Chapter 9, Working with Generics, allows us to write very flexible and reusable code that avoids duplication. In this chapter, we will examine how Swift implements generics. We will also look at the proper ways to use generics in our code.

Chapter 10, Working with Closures, examines how to define and use closures in our code. We will conclude this chapter with a section on how to avoid strong reference cycles with closures. Closures in Swift are similar to blocks in Objective-C, except that they have a much cleaner and easier-to-use syntax.

Chapter 11, Using Mix and Match, examines mix and match and demonstrates how we can include Swift code in our Objective-C projects and Objective-C code in our Swift projects. With all of the apps and frameworks written in Objective-C, it was important to allow Swift and Objective-C code to work together.

Chapter 12, Concurrency and Parallelism in Swift, shows how to use both Grand Central Dispatch (GCD) and Operation Queues to add concurrency and parallelism to our applications. Understanding and knowing how to add concurrency and parallelism to our apps can significantly enhance the user experience.

Chapter 13, Swift Formatting and Style Guide, defines a style guide for the Swift language that can be a template for enterprise developers that need to create a style guide. Most enterprises have style guides for the various languages that they develop in.

Chapter 14, Network Development with Swift, looks at the Apple APIs to connect to remote severs and how to best use them. Network development can be both fun and challenging.

Chapter 15, Adopting Design Patterns in Swift, examines how to implement some of the more common design patterns in Swift. A design pattern identifies a common software development problem and provides a strategy for dealing with it.

To follow along with the examples in this book, the reader will need to have a Mac computer with OS X 10.10 or higher installed. They will also need to install Xcode version 6.3.1 or higher with Swift version 1.2 or higher.

This book is intended for individuals looking for a book that not only gives them a solid introduction to the Swift programming language, but will also cover advanced topics such as ARC, Design Patterns, and Concurrency in depth. This book is written for the developer that learns best by looking at and working with code, because each concept covered in the book is backed by example code written to give the reader a good understanding of the current topic and to demonstrate how to properly implement it.

In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "To define a constant, you use the keyword let and to define a variable you use the keyword var."

A block of code is set as follows:

// Constants
let freezingTemperatureOfWaterCelsius = 0
let speedOfLightKmSec = 300000

// Variables
var currentTemperature = 22
var currentSpeed = 55

New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "As we can see in the Timeline sidebar, our application will print the message Hello World! to the console."

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