Book Image

Swift 3 Object-Oriented Programming - Second Edition

By : Gaston C. Hillar
Book Image

Swift 3 Object-Oriented Programming - Second Edition

By: Gaston C. Hillar

Overview of this book

Swift has quickly become one of the most-liked languages and developers’ de-facto choice when building applications that target iOS and macOS. In the new version, the Swift team wants to take its adoption to the next level by making it available for new platforms and audiences. This book introduces the object-oriented paradigm and its implementation in the Swift 3 programming language to help you understand how real-world objects can become part of fundamental reusable elements in the code. This book is developed with XCode 8.x and covers all the enhancements included in Swift 3.0. In addition, we teach you to run most of the examples with the Swift REPL available on macOS and Linux, and with a Web-based Swift sandbox developed by IBM capable of running on any web browser, including Windows and mobile devices. You will organize data in blueprints that generate instances. You’ll work with examples so you understand how to encapsulate and hide data by working with properties and access control. Then, you’ll get to grips with complex scenarios where you use instances that belong to more than one blueprint. You’ll discover the power of contract programming and parametric polymorphism. You’ll combine generic code with inheritance and multiple inheritance. Later, you’ll see how to combine functional programming with object-oriented programming and find out how to refactor your existing code for easy maintenance.
Table of Contents (17 chapters)
Swift 3 ObjectOriented Programming - Second Edition
Credits
About the Author
Acknowledgement
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Declaring classes that adopt protocols


Now, we will declare a class that specifies that it conforms to the ComicCharacter protocol in its declaration in the Playground. Instead of specifying a superclass, the class declaration includes the name of the previously declared ComicCharacter protocol after the class name (AngryDog) and the colon (:). We can read the class declaration as "the AngryDog class conforms to the ComicCharacter protocol."

However, the class doesn't implement any of the required properties and methods specified in the protocol, so it doesn't really conform to the ComicCharacter protocol, as shown in the following code. The code file for the sample is included in the swift_3_oop_chapter_05_02 folder:

    open class AngryDog: ComicCharacter { 
 
    } 

The Playground execution will fail because the AngryDog class doesn't conform to the ComicCharacter protocol, so the Swift compiler generates the following errors and notes. We will see similar error messages...