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

Swift's type system


Swift is a strongly typed language, which means that every constant and variable is defined with a specific type. Only values of matching types can be assigned to them. So far, we have taken advantage of a feature of Swift called Type Inference. This means that the code does not have to explicitly declare a type if it can be inferred from the value being assigned to it during the declaration.

Without Type Inference, the name variable declaration from before would be written as follows:

var name: String = "Sarah"

This code is explicitly declaring name as the type String with the value Sarah. A constant or variable's type can be specified by adding a colon (:) and a type after its name.

A string is defined by a series of characters. This is perfect for storing text, as in our name example. The reason that we don't need to specify the type is that Sarah is a string literal. Text surrounded by quotation marks is a string literal and can be inferred to be of the type String....