Table of Contents

Swift 2 Design Patterns

Credits

About the Author

About the Reviewers

www.PacktPub.com

Support files, eBooks, discount offers, and more

Why subscribe?

Free access for Packt account holders

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the example code

Downloading the color images of this book

Errata

Piracy

eBooks, discount offers, and more

Questions

1. Creational Patterns

The prototype pattern

Roles

Design

Participants

Collaborations

Illustration

Implementation

Usage

The factory method pattern

Roles

Design

Participants

Illustration

Implementation

Usage

The singleton pattern

Roles

Design

Participants

Collaborations

Illustration

Implementation

Usage

The abstract factory pattern

Roles

Design

Participants

Collaborations

Illustration

Implementation

Usage

The builder pattern

Roles

Design

Participants

Collaborations

Illustration

Implementation

Usage

Implementation using closures

Summary

2. Structural Patterns – Decorator, Proxy, and Bridge

Static and dynamic composition

The decorator pattern

Roles

Design

Participants

Collaboration

Sample

Implementation

Usage

The proxy pattern

Roles

Design

Participants

Collaboration

Illustration

Implementation

Usage

The bridge pattern

Roles

Design

Participants

Collaboration

Illustration

Implementation

Usage

Summary

3. Structural Patterns – Composite and Flyweight

The composite pattern

Roles

Design

Participants

Collaboration

Illustration

Implementation

Implementation of the VODComponent

Implementation of the VODItem leaf

Implementation of the VODCategory composite

Usage

The flyweight pattern

Roles

Design

Participants

Collaboration

Illustration

Implementation

Usage

Performance results

Summary

4. Structural Patterns – Adapter and Facade

The adapter pattern

Roles

Design

Participants

Collaboration

Illustration

Implementing our first prototype

Implementation

Implementation of our adaptees

Implementation of the SamSingAdapter class

Implementation of the PearAdapter class

The facade pattern

Roles

Design

Participants

Collaboration

Illustration

Implementation of the facade

Summary

5. Behavioral Patterns – Strategy, State, and Template Method

The strategy pattern

Roles

Design

Participants

Collaboration

Illustration

Implementation

The state pattern

Role

Design

Participants

Collaboration

Illustration

Implementation

The template method

Role

Design

Participants

Collaboration

Illustration

Implementation

Summary

6. Behavioral Patterns – Chain of Responsibility and Command

The chain of responsibility pattern

Roles

Design

Participants

Collaboration

Illustration

Implementation

The command pattern

Roles

Design

Participants

Collaboration

Illustration

Implementation

Comparison between the chain of responsibility and command patterns

Summary

7. Behavioral Patterns – Iterator, Mediator, and Observer

The iterator pattern

Roles

Design

Participants

Collaboration

Illustration

Implementation

The mediator pattern

Roles

Design

Participants

Collaboration

Illustration

Implementation

The observer pattern

Roles

Design

Participants

Collaboration

Illustration

Implementation

Summary

8. Behavioral Patterns – Visitor, Interpreter, and Memento

The visitor pattern

Roles

Design

Participants

Collaboration

Illustration

Implementation

The interpreter pattern

Roles

Design

Participants

Collaboration

Illustration

Implementation

The memento pattern

Roles

Design

Participants

Collaboration

Illustration

Implementation

Comparing the three patterns

Summary

Index

Swift 2 Design Patterns

Swift 2 Design Patterns

Copyright © 2015 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: October 2015

Production reference: 1231015

Published by Packt Publishing Ltd.

Livery Place

35 Livery Street

Birmingham B3 2PB, UK.

ISBN 978-1-78588-761-1

www.packtpub.com

Credits

Author

Julien Lange

Reviewers

Vladimir Pouzanov

Victor Sigler

Ye Xiaodong

Acquisition Editor

Tushar Gupta

Content Development Editor

Shali Deeraj

Technical Editor

Saurabh Malhotra

Copy Editors

Rashmi Sawant

Sneha Singh

Project Coordinator

Kinjal Bari

Proofreader

Safis Editing

Indexer

Hemangini Bari

Graphics

Disha Haria

Jason Monteiro

Abhinash Sahu

Production Coordinator

Komal Ramchandani

Cover Work

Komal Ramchandani

About the Author

Julien Lange is a 34-year-old IT expert in software engineering. He started developing on an Amstrad CPC464 with the BASIC language when he was 7 years old. He later learned Visual Basic 3/4, then VB.NET, and then C#. For several years until the end of his education, he developed and maintained several e-business websites based on PHP and ASP.NET. After his graduation, he continued to learn more and more about software, which included software architecture and project management, and always tried to acquire new skills. Since 2011, he has been working as an IT project manager on the lead management middleware of DSI Axa France (a French insurance company). This middleware is based on the SOA architecture. As this middleware is consumed by frontend users exposed on the Internet, performance is the top priority each time he delivers a new release of the system. Scalability and robustness are really important in his everyday work.

He first developed an interest in mobile development in 2009. After discovering the massive potential of iPhone games and software, he decided to find an improved game engine, which would allow him to concentrate only on the main purpose of a game: developing a game and not a game engine. His choice was Unity 3D. Later, he took some time to learn the native iOS Objective-C language, which was quite difficult for him due to its language particularity and finally learned Swift since its first apparition in 2014. In addition to his main work as an IT consultant, he created iXGaming.com in December 2010. He currently has several projects in mind, including a game based on a French board game and a new website that delivers new services to developers. He is searching for a few partners to work with.

After reviewing several books by Packt Publishing, I decided to write a book for them. I would especially like to thank all the members of Packt Publishing, including Shali, Tushar, and Sam. I would also thank, every reviewer and especially Victor Sigler for their times reviewing this book. Also, I would to thank my family, and most of all my wife, for allowing me to take some time to write this book. I would also like to thank a few people with whom I work everyday: Adrien D, Alain De L, Juliette O., Raphael D, Stephane D, Helmi C, and Christelle P.

About the Reviewers

Vladimir Pouzanov is a systems engineer and embedded enthusiast. He has spent countless hours hacking different mobile hardware, porting Linux to various devices that were not supposed to run it, and toying around outside the iOS sandbox. He has also been a professional iOS consultant and has been developing applications based on iOS ever since the first Apple iPhones became available. Later on, he switched his professional interest to systems engineering and cloud computing, but he still keeps a close eye on the mobile and embedded world.

I'd like to give credit to my wife for her amazing support when I was working on the review and sharing my attention between her, our daughter, and the book.

Victor Sigler is an iOS software engineer with experience of developing consumer and enterprise mobile applications. He loves everything that is related to Apple. He is passionate about Swift and the world of programming contests. He enjoys writing about iOS development on his blog at http://www.vsigler.com and helps people solve their queries on Stack Overflow. He can be found on Twitter at @Vkt0r.

Ye Xiaodong is a full-stack software engineer and technical director of zai360.com, an O2O company that provides a recyclables collection service for Chinese family customers on a periodical basis. He has 7 years of application development experience working for start-ups and leading companies across the world on iOS, Android, Windows Phone, Symbian, and Meego. He has developed lots of iOS applications; designed, created, and maintained iOS libraries and Xcode plugins; and contributed to open source projects, as he is passionate about bringing the latest features to applications. He has worked as a technical reviewer for the book Mastering Swift, Packt Publishing.

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 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.

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.

Preface

This book will help you understand when and how to implement the 23 patterns, as described by the gang of four (GoF), with the new language provided by Apple: Swift.

The main idea behind this book is to make it a reference book for implementing a specific pattern. This is the reason why I have divided this book into three categories: creational, structural, and behavioral patterns. For each category, you will find a chapter with a common structure: roles, a UML class diagram, participants, collaboration, illustration, and implementation with Swift.

This structure is an easy way to find the answers that you may ask yourself. In this book, I will first introduce you to the five creational patterns, followed by seven structural patterns, and then conclude with the eleven behavioral patterns, as defined by the GoF.

What this book covers

Chapter 1, Creational Patterns, introduces you to the five patterns of a creational pattern category: the prototype, factory method, singleton, abstract factory, and builder patterns.

Chapter 2, Structural Patterns – Decorator, Proxy, and Bridge, introduces you to structural patterns and helps you explore the decorator, proxy, and bridge patterns.

Chapter 3, Structural Patterns – Composite and Flyweight, teaches you how to deal with the structure of multiple objects using the composite and flyweight patterns.

Chapter 4, Structural Patterns – Adapter and Facade, teaches you how to join the two types that were not designed to work with each other together, thanks to the adapter pattern. Then, you'll learn how the facade pattern can help you simplify the interface of a set of complex systems.

Chapter 5, Behavioral Patterns – Strategy, State, and Template Method, introduces you to the behavioral patterns. In this chapter, we will discuss the strategy, state, and template method patterns.

Chapter 6, Behavioral Patterns – Chain of Responsibility and Command, introduces you to two other behavioral patterns that are concerned with passing requests to an appropriate object that will then execute the action.

Chapter 7, Behavioral Patterns – Iterator, Mediator, and Observer, provides a way to implement communication between objects while keeping their independence and anonymity.

Chapter 8, Behavioral Patterns – Visitor, Interpreter, and Memento, concludes with the discovery and implementation of the 23 patterns, as defined by the GoF.

What you need for this book

The only requirement for this book is to have Xcode 7 installed on your Mac computer. All the code provided has been written, compiled, and tested with Swift 2. You don't need any other software to follow the examples provided in this book. All samples in these book have been written using a OSX Command line tool project or a Playground file.

Who this book is for

This book is intended for beginners as well as senior developers who want to take the next step in the software engineering industry.

This book will help you learn about the difference between a low-level programmer and a programmer with design pattern knowledge. You can apply this knowledge with Swift in Xcode to design scalable and flexible apps or games for iOS and Mac. As design patterns are not the exclusive reserve of Swift, but can be used by any other language, this is the knowledge that