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

Printing to the console


It is very useful to write output to a log so that you can trace the behavior of code. As a codebase grows in complexity, it gets hard to follow the order in which things happen and exactly what the data looks like as it flows through the code. Playgrounds help a lot with this but it is not always enough.

In Swift, this process is called printing to the console. To do this, you use something called print. It is used by writing print followed by text surrounded by parentheses. For example, to print Hello World! to the console, the code would look like this:

print("Hello World!")

If you put that code in a playground, you would see Hello World! written in the results pane. However, this is not truly the console. To view the console, you can go to View | Debug Area | Show Debug Area. A new view will appear at the bottom of the window and it will contain all text the code has printed to the console:

Not only can you print static text to the console, you can also print out...