Book Image

Swift 4 Protocol-Oriented Programming - Third Edition

By : Jon Hoffman
Book Image

Swift 4 Protocol-Oriented Programming - Third Edition

By: Jon Hoffman

Overview of this book

Swift has become the number one language used in iOS and macOS development. The Swift standard library is developed using protocol-oriented programming techniques, generics, and first-class value semantics; therefore, every Swift developer should understand these powerful concepts and how to take advantage of them in their application design. This book will help you understand the differences between object-oriented programming and protocol-oriented programming. It will demonstrate how to work with protocol-oriented programming using real-world use cases. You will gain a solid knowledge of the various types that can be used in Swift and the differences between value and reference types. You will be taught how protocol-oriented programming techniques can be used to develop very flexible and easy-to-maintain code. By the end of the book, you will have a thorough understanding of protocol-oriented programming and how to utilize it to build powerful and practical applications.
Table of Contents (15 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Defining an extension


An extension is defined by using the extension keyword followed by the name of the type you are extending. We then put the functionality that we are adding to the type between curly brackets. The following example shows how to define an extension:

extension String { 
  // Add functionality here 
} 

The previous example would add an extension to the String type from the Swift standard library. Since we can extend any type, we can use extensions to add functionality to types from the Swift standard library, types from frameworks, or our own custom types. While we can use extensions to add functionality to our own custom types, it is usually better to add the functionality directly to the type itself. The reason for this is that our code is easier to maintain if all the functionality (code) for our custom types is located together.

If we are adding functionality to a framework and we have the code for that framework, it is still better to add the functionality with an extension...