Book Image

Swift Functional Programming - Second Edition

By : Dr. Fatih Nayebi
Book Image

Swift Functional Programming - Second Edition

By: Dr. Fatih Nayebi

Overview of this book

Swift is a multi-paradigm programming language enabling you to tackle different problems in various ways. Understanding each paradigm and knowing when and how to utilize and combine them can lead to a better code base. Functional programming (FP) is an important paradigm that empowers us with declarative development and makes applications more suitable for testing, as well as performant and elegant. This book aims to simplify the FP paradigms, making them easily understandable and usable, by showing you how to solve many of your day-to-day development problems using Swift FP. It starts with the basics of FP, and you will go through all the core concepts of Swift and the building blocks of FP. You will also go through important aspects, such as function composition and currying, custom operator definition, monads, functors, applicative functors,memoization, lenses, algebraic data types, type erasure, functional data structures, functional reactive programming (FRP), and protocol-oriented programming(POP). You will then learn to combine those techniques to develop a fully functional iOS application from scratch
Table of Contents (19 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Dedication
Preface

Optional chaining


Optional chaining is a process to query and call properties, methods, and subscripts on an optional that may currently be nil. Optional chaining in Swift is similar to messaging nil in Objective-C but in a way that works for any type and can be checked for success or failure.

The following example presents two different classes. One of the classes, Person, has a property of type of Optional (residence), which wraps the other class type Residence:

class Residence { 
    var numberOfRooms = 1 
} 

class Person { 
    var residence: Residence? 
} 

We will create an instance of the Person class, sangeeth:

let residence = Residence() 
residence.numberOfRooms = 5 

let sangeeth = Person() 
sangeeth.residence = residence 

To check for numberOfRooms, we need to use the residence property of the Person class, which is an optional. Optional chaining enables us to go through Optionals as follows:

if let roomCount = sangeeth.residence?.numberOfRooms { 
    // Use the roomCount 
    print...