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

Copy-on-write


When an instance of a value type, such as a structure, is assigned to another variable, that second variable receives a copy of the instance. This means that, if we had an array that contained 50,000 elements, then at runtime we would need to copy all 50,000 elements when we assigned the array to a second variable or if we passed it to another part of our code. This can severely impact our performance; however, with Swift built-in data structures such as the array this impact is reduced because of Copy-on-write.

With Copy-on-write, Swift does not make a second copy of the data structure until a change is made to that data structure. Therefore, if we pass an array of 50,000 elements to another part of our code, and that code does not actually make any changes to the array, we will avoid the runtime overhead of copying all the elements.

Unfortunately, Copy-on-write is only implemented with certain types in the Swift Standard library and does not come free with all value types....