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

Working with typecasting and polymorphism


We can use the same method to cause different things to happen according to the class on which we invoke the method. In object-oriented programming, this feature is known as polymorphism.

For example, consider that we defined a talk method in the Animal class. The different subclasses of Animal must override this method to provide their own implementation of talk.

The Dog class overrode this method to print the representation of a dog barking, that is, a Woof message. On the other hand, a Cat class will override this method to print the representation of a cat meowing, that is, a Meow message.

Now, let's think about a CartoonDog class that represents a dog that can really talk as part of a cartoon. The CartoonDog class would override the talk method to print a Hello message because the dog can really talk.

Thus, depending on the type of instance, we will see a different result after invoking the same method with the same arguments even when all of them...