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

Understanding property observers


Each superhero has a running speed score that determines how fast he will move when running; therefore, we will add a public runningSpeedScore property. We will change the initializer code to set an initial value for the new property. However, this new property has some specific requirements.

Whenever the running speed score is about to change, it will be necessary to trigger a few actions. In addition, we have to trigger other actions after the value for this property changes. We might consider adding code to a setter method combined with a related property, run code before we set the new value to the related property, and then run code after we set the new value. However, Swift allows us to take advantage of property observers that make it easier to run the code before and after the running speed score changes.

We can define a public runningSpeedScore property with both a willSet and didSet methods. After we create an instance of the new version of the SuperHero...