Book Image

Learning Swift Second Edition - Second Edition

By : Andrew J Wagner
Book Image

Learning Swift Second Edition - Second Edition

By: Andrew J Wagner

Overview of this book

Swift is Apple’s new programming language and the future of iOS and OS X app development. It is a high-performance language that feels like a modern scripting language. On the surface, Swift is easy to jump into, but it has complex underpinnings that are critical to becoming proficient at turning an idea into reality. This book is an approachable, step-by-step introduction into programming with Swift for everyone. It begins by giving you an overview of the key features through practical examples and progresses to more advanced topics that help differentiate the proficient developers from the mediocre ones. It covers important concepts such as Variables, Optionals, Closures, Generics, and Memory Management. Mixed in with those concepts, it also helps you learn the art of programming such as maintainability, useful design patterns, and resources to further your knowledge. This all culminates in writing a basic iOS app that will get you well on your way to turning your own app ideas into reality.
Table of Contents (19 chapters)
Learning Swift Second Edition
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Constants and variables


Now, we are ready to dive into the basics of the Objective-C language. Objective-C has constants and variables very similar to Swift but they are declared and worked with slightly differently. Let's take a look at declaring a variable in both Swift and Objective-C:

var number: Int
int number;

The first line should look familiar, as it is Swift. The Objective-C version doesn't actually look all that different. The important difference is that the type of the variable is declared before the name instead of after. It is also important to note that Objective-C has no concept of type inference. Every time a variable is declared, it must be given a specific type. You will also see that there is a semicolon after the name. This is because every line of code in Objective-C must end with a semicolon. Lastly, you should notice that we have not explicitly declared number as a variable. This is because all information is assumed to be variable in Objective-C unless specified otherwise...