Table Of Content[ 1 ]
Protocol-Oriented Programming
with Swift
Build fast and powerful applications by exploiting the
power of protocol-oriented programming in Swift
Jon Hoffman
BIRMINGHAM - MUMBAI
Protocol-Oriented Programming with Swift
Copyright © 2016 Packt Publishing
All rights reserved. No part of this book may be reproduced, stored in a retrieval
system, or transmitted in any form or by any means, without the prior written
permission of the publisher, except in the case of brief quotations embedded in
critical articles or reviews.
Every effort has been made in the preparation of this book to ensure the accuracy
of the information presented. However, the information contained in this book
is sold without warranty, either express or implied. Neither the author nor Packt
Publishing, and its dealers and distributors will be held liable for any damages
caused or alleged to be caused directly or indirectly by this book.
Packt Publishing has endeavored to provide trademark information about all of the
companies and products mentioned in this book by the appropriate use of capitals.
However, Packt Publishing cannot guarantee the accuracy of this information.
First published: February 2016
Production reference: 1190216
Published by Packt Publishing Ltd.
Livery Place
35 Livery Street
Birmingham B3 2PB, UK.
ISBN 978-1-78588-294-4
www.packtpub.com
Credits
Author Project Coordinator
Jon Hoffman Dinesh Rathe
Reviewer Proofreader
Chuck Gaffney Safis Editing
Commissioning Editor Indexer
Wilson D'souza Monica Ajmera Mehta
Acquisition Editor Graphics
Tushar Gupta Disha Haria
Content Development Editor Production Coordinator
Sumeet Sawant Nilesh Mohite
Technical Editor Cover Work
Jayesh Sonawane Nilesh Mohite
Copy Editors
Stephen Copestake
Akshata Lobo
About the Author
Jon Hoffman has over 20 years of experience in the field of information technology.
Over these 20 years, Jon has worked in the areas of system administration, network
administration, network security, application development, and architecture.
Currently, Jon works as a senior software engineer for Syn-Tech Systems.
Jon has been developing extensively for the iOS platform since 2008. This includes
several apps that he has published in the app store—apps that he wrote for third
parties and numerous enterprise applications.
Packt Publishing published Jon's first book, iOS and OS X Network Programming, in
January 2014.
What really drives Jon is the challenges in the Information Technology field and
there is nothing more exhilarating to him than overcoming a challenge. Some of Jon's
other interests are watching baseball (go Sox) and basketball (go Celtics). Jon also
really enjoys tae kwon do where he and his oldest daughter Kailey earned their black
belts together early in 2014. Kim (his wife) earned her black belt in December 2014
and his youngest daughter is currently working towards her black belt.
I would like to thank my wonderful wife Kim, without whose
support, encouragement, patience, and understanding, this book
would never have been written. I would also like to thank my two
wonderful daughters Kailey and Kara who have both been my
inspiration and driving force since the days they were born.
About the Reviewer
Chuck Gaffney is the owner of the website/store and indie studio Chuck's Anime
Shrine as well as Anime.FM. He is a programmer by trade, ranging from games,
non-games, VR, AR, and mobile applications. He has worked with iOS native
(Swift/Objective-C/XCode) code, Flash animation, and game development as well
as web design. Recently, he has been working almost exclusively in Unity/C#,
making mobile applications that work with games, non-games, AR, VR, and third-
party API integrations.
Interestingly, he is also a professional voice actor with work in games, museum
experiences, movie dubs, and more. He is the owner of the long running fan site, store,
and indie game studio Chuck's Anime Shrine. He recently worked with two major
NYC studios and with clients that include some financial giants and the Late Show
with Steven Colbert. He is currently developing an app for a major beer company.
I would like to thank my fiancée Danielle for putting up with the
late nights and all nighters that come with the territory of being a
programmer, voice actor, and business owner.
www.PacktPub.com
Support files, eBooks, discount offers, and more
For support files and downloads related to your book, please visit www.PacktPub.com.
Did you know that Packt offers eBook versions of every book published, with PDF
and ePub files available? You can upgrade to the eBook version at www.PacktPub.
com and as a print book customer, you are entitled to a discount on the eBook copy.
Get in touch with us at [email protected] for more details.
At www.PacktPub.com, you can also read a collection of free technical articles, sign
up for a range of free newsletters and receive exclusive discounts and offers on Packt
books and eBooks.
TM
https://www2.packtpub.com/books/subscription/packtlib
Do you need instant solutions to your IT questions? PacktLib is Packt's online digital
book library. Here, you can search, access, and read Packt's entire library of books.
Why subscribe?
• Fully searchable across every book published by Packt
• Copy and paste, print, and bookmark content
• On demand and accessible via a web browser
Free access for Packt account holders
If you have an account with Packt at www.PacktPub.com, you can use this to access
PacktLib today and view 9 entirely free books. Simply use your login credentials for
immediate access.
Table of Contents
Preface v
Chapter 1: Object-Oriented and Protocol-Oriented Programming 1
Swift as an object-oriented programming language 2
Swift as a protocol-oriented programming language 13
Summarizing protocol-oriented programming and object-oriented
programming 18
Object-oriented programming versus protocol-oriented programming 19
Protocol and protocol extensions versus superclasses 19
Implementing drink types 22
Value types vs reference types 24
The winner is... 25
Summary 26
Chapter 2: Our Type Choices 27
The class 28
The structure 30
The enumerations 31
The tuple 36
Protocols 37
Value versus class types 38
Recursive data types (reference types only) 44
Inheritance (reference types only) 46
Swift built-in data types and data structures 49
Summary 50
Chapter 3: Catching Our Errors 51
Using the guard statement 52
Error handling 55
Error handling with return values 56
[ i ]
Table of Contents
Error handling with NSError 58
Error handling with Swift 2 61
Representing errors 62
Throwing errors 63
Catching errors 67
When to use error handling 70
Summary 72
Chapter 4: All about the Protocol 73
Protocol syntax 75
Defining a protocol 75
Property requirements 76
Method requirements 76
Optional requirements 77
Protocol inheritance 78
Protocol composition 79
Using protocols as a type 81
Polymorphism with protocols 83
Type casting with protocols 84
Associated types with protocols 85
Delegation 87
Designing and developing with protocols 90
Summary 95
Chapter 5: Let's Extend Some Types 97
Defining an extension 99
Protocol extensions 101
Text validation 106
Summary 114
Chapter 6: Adopting Design Patterns in Swift 115
What are design patterns? 116
Creational patterns 117
The singleton design pattern 118
Understanding the problem 118
Understanding the solution 119
Implementing the singleton pattern 119
The builder design pattern 121
Understanding the problem 121
Understanding the solution 121
Implementing the builder pattern 122
The factory method pattern 127
Understanding the problem 127
[ ii ]
Table of Contents
Understanding the solution 127
Implementing the factory method pattern 128
Structural design patterns 131
The bridge pattern 131
Understanding the problem 131
Understanding the solution 132
Implementing the bridge pattern 132
The façade pattern 136
Understanding the problem 136
Understanding the solution 136
Implementing the façade pattern 137
The proxy design pattern 139
Understanding the problem 139
Understanding the solution 140
Implementing the proxy pattern 140
Behavioral design patterns 142
The command design pattern 143
Understanding the problem 143
Understanding the solution 143
Implementing the command pattern 143
The strategy pattern 146
Understanding the problem 146
Understanding the solution 146
Implementing the strategy pattern 146
The observer pattern 148
Understanding the problem 148
Understanding the solution 148
Implementing the observer pattern 149
Summary 154
Chapter 7: Case Studies 155
Logging service 156
Requirements 157
The design 157
Conclusion 166
Data access layer with SQLite.swift 166
Requirements 167
The design 168
Connection layer 169
Data model layer 171
Data helper layer 172
Conclusion 181
Calculator application 181
Requirements 182
[ iii ]
