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 associated types in protocols


Now, we want to declare a PartyProtocol protocol and make the generic Party<AnimalElement> class conform to this new protocol. The main challenge is to specify the type for both the method arguments and returned values. In the generic class, we will use the generic type parameter, but protocols don't allow us to use them.

Associated types allow us to solve the problem. We can declare one or more associated types as part of the protocol definition. In this case, we just need one associated type to provide us with a placeholder name---also known as alias---to a type that we will use as part of the protocol and that will be specified during the protocol implementation, that is, when we declare a class that conforms to the protocol. It is just necessary to use the associatedtype keyword followed by the desired name for the associated type, and then, we can use the name in our requirements' declarations.

The following lines show the declaration of the...