Chapter 1, Taking the First Steps with Swift, gives a brief introduction to the Swift language. We will also cover the basic Swift language syntax and discuss proper language styles.

Chapter 2, Learning About Variables, Constants, Strings, and Operators, shows how to use variables and constants in Swift. We will also look at the various data types and how to use operators in Swift.

Chapter 3, Using Swift Collections and the Tuple Type, looks at how we can use the Swift collection types to store related data. These collection types are the dictionary, array and set types.

Chapter 4, Control Flow and Functions, covers control flow and functions in Swift. It is essential to understand the concepts in this chapter before going on. Every application that we write, beyond the simple Hello World applications, will rely very heavily on the control flow statements and functions.

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

Chapter 6, Using Protocols and Protocol Extensions, covers both protocols and protocol extensions in detail since protocols are very important to the Swift language. Having a solid understanding of them will help us write flexible and reusable code.

Chapter 7, Protocol-Oriented Design, covers the best practices of protocol-oriented Design with Swift. It will be a brief overview of what is covered in my Swift 3 Protocol-Oriented Programming book.

Chapter 8, Writing Safer Code with Error Handling, looks at Swift's error-handling features. This feature is really important for writing safe code. While we are not required to use this feature in our custom types however it does give us a uniform manner to handle and respond to the error. Apple has also started to use this error handling in their frameworks. It is recommended that we use error handling in our code.

Chapter 9, Custom Subscripting, discusses 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 10, Using Optional Types, explains what optional types really are, what the various ways to unwrap them are, and optional chaining. For a developer who is just learning Swift, optional types can be one of the most confusing items to learn.

Chapter 11, Working with Generics, explains how Swift implements generics. Generics allow us to write very flexible and reusable code that avoids duplication.

Chapter 12, Working with Closures, teaches us how to define and use closures in our code. Closures in Swift are similar to blocks in Objective-C except that they have a much cleaner and easier to use syntax. We will conclude this chapter with a section on how to avoid strong reference cycles with closures.

Chapter 13, Using C Libraries with Swift, explains how we can link and use standard C libraries with our Swift applications. This gives Swift developers access to all of the same libraries that Linux C developers have access to.

Chapter 14, Concurrency and Parallelism in Swift, shows how to use Grand Central Dispatch (GCD) 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 15, Swift's Core Libraries, explains how to use the Swift core libraries, including reading/writing files, network primitives, and JSON parsing.

Chapter 16, Swift on Single Board Computers, shows how we can use Swift to develop IoT devices and robots using a single board computer.

Chapter 17, Swift Formatting and Style Guide, defines a style guide for the Swift language that can be used as a template for enterprise developers who need to create a style guide, since most enterprises have style guides for the various languages that they develop in.

Chapter 18, Adopting Design Patterns in Swift, shows you 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 samples in this book, the reader will need a computer that has Ubuntu 14.04, 15.10, 16.04, or 16.10 installed. To follow along with the samples in Chapter 16, Swift on Single Board Computers, the reader will need a BeagleBone Black or Green single board computer and the additional components mentioned in the chapter.

Swift is a modern, fast, and safe open source language created by Apple. This book is for Linux developers who are interested in learning how to use Swift to quickly create exciting applications for the desktop, server, and embedded Linux platforms. This book will be written for developers who learn best by working with code, as every topic discussed will be reinforced with code samples.

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: "We can change the value of the highTemperture variable without an error because it is a variable"

A block of code is set as follows:

var x = 3.14      // Double type 
var y = "Hello"   // String type 
var z = true      // Boolean type

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

<head> 
<script src="d3.js" charset="utf-8"></script>  
  <meta charset="utf-8"> 
  <meta name="viewport" content="width=device-width"> 
  <title>JS Bin</title> 
</head>

Any command-line input or output is written as follows:

sudo mkdir swift

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: "In order to download new modules, we will go to Files | Settings | Project Name | Project Interpreter."

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