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

Protocol extensions


Protocols, like other types, can be extended. Protocol extensions can be used to provide common functionality to all types that conform to a particular protocol. This gives us the ability to add functionality to any type that conforms to a protocol rather than adding the functionality to each individual type or through a global function. Protocol extensions, like regular extensions, also give us the ability to add functionality to types that we do not have the source code for.

Protocol-oriented programming and frameworks such as GameplayKit rely heavily on protocol extensions. Without protocol extensions, if we wanted to add specific functionality to a group of types that conformed to a protocol, we would have to add the functionality to each of the types. If we were using reference types (classes), we could create a class hierarchy, but, as we mentioned earlier, that is not possible with value types. Apple has stated that we should prefer value types to reference types...