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Learning Swift Second Edition

Learning Swift Second Edition

By : Andrew J Wagner
5 (1)
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Learning Swift Second Edition

Learning Swift Second Edition

5 (1)
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 (14 chapters)
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13
Index

Value types versus reference types


All variables and constants in Swift are stored in memory. In fact, unless you explicitly write data to the file system, everything you create is going to be in memory. In Swift, there are two different categories of types. These two categories are value types and reference types. The only way in which they differ is in the way they behave when they get assigned to new variables, passed into methods, or captured in closures. Essentially, they only differ when you try to assign a new variable or constant to the value of an existing variable or constant.

A value type is always copied when being assigned somewhere new while a reference type is not. Before we look at exactly what that means in more detail, let's go over how we determine if a type is a value type or a reference type.

Determining value type or reference type

A value type is any type that is defined as either a structure or an enumeration, while all classes are reference types. This is easy to determine...

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