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

Customizing initialization


We want to initialize instances of the Circle class with the radius value. In order to do so, we can take advantage of customized initializers. Initializers aren't methods, but we will write them with syntax that is very similar to the instance methods. They will use the init keyword to differentiate from instance methods, and Swift will execute them automatically when we create an instance of a given type. Swift runs the code within the initializer before any other code within a class.

We can define an initializer that receives the radius value as an argument and use it to initialize a property with the same name. We can define as many initializers as we want to, and therefore, we can provide many different ways of initializing a class. In this case, we just need one initializer.

The following lines create a Circle class and define an initializer within the class body. The code file for the sample is included in the swift_3_oop_chapter_02_02 folder:

    class Circle...