Book Image

Mastering macOS Programming.

By : Stuart Grimshaw, Gregory Casamento
Book Image

Mastering macOS Programming.

By: Stuart Grimshaw, Gregory Casamento

Overview of this book

macOS continues to lead the way in desktop operating systems, with its tight integration across the Apple ecosystem of platforms and devices. With this book, you will get an in-depth knowledge of working on macOS, enabling you to unleash the full potential of the latest version using Swift 3 to build applications. This book will help you broaden your horizons by taking your programming skills to next level. The initial chapters will show you all about the environment that surrounds a developer at the start of a project. It introduces you to the new features that Swift 3 and Xcode 8 offers and also covers the common design patterns that you need to know for planning anything more than trivial projects. You will then learn the advanced Swift programming concepts, including memory management, generics, protocol orientated and functional programming and with this knowledge you will be able to tackle the next several chapters that deal with Apple’s own Cocoa frameworks. It also covers AppKit, Foundation, and Core Data in detail which is a part of the Cocoa umbrella framework. The rest of the book will cover the challenges posed by asynchronous programming, error handling, debugging, and many other areas that are an indispensable part of producing software in a professional environment. By the end of this book, you will be well acquainted with Swift, Cocoa, and AppKit, as well as a plethora of other essential tools, and you will be ready to tackle much more complex and advanced software projects.
Table of Contents (28 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Dedication
Preface
18
LLDB and the Command Line

Value and reference types


The basic data types of Swift, such as Int, Double, and Bool, are said to be value types. This means that, when passing a value to a function (including assignment of variables and constants), it is copied into its new location:

var x1 = 1 
var y1 = x1 
y1 = 2 
x1 == 1 // true 

However, this concept extends to String, Array, Dictionary, and many other objects that, in some languages, notably Objective C, are passed by reference. Passing by reference means that we pass a pointer to the actual object itself, as an argument, rather than just copy its value:

var referenceObject1 = someValue 
var referenceObject2 = referenceObject1 
referenceObject2 = someNewValue 

These two variables now point to the same instance.

While this pattern is frequently desirable, it does leave a lot of variables sharing the same data--if you change one, you change the others. And that's a great source of bugs.

So, in Swift, we have many more value types than reference types. This even extends...