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Learning Swift Second Edition

Learning Swift Second Edition - Second Edition

By : Andrew J Wagner
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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

Throwing errors


Before we talk about handling an error, we need to discuss how we can signal that an error has occurred in the first place. The term for this is throwing an error.

Defining an error type

The first part of throwing an error is defining an error that we can throw. Any type can be thrown as an error as long as it implements the ErrorType protocol, as shown:

struct SimpleError: ErrorType {}

This protocol doesn't have any requirements, so the type just needs to list it as a protocol it implements. It is now ready to be thrown from a function or method.

Defining a function that throws an error

Let's define a function that will take a string and repeat it until it is at least a certain length. This will be very simple to implement but there will be a problem scenario. If the passed in string is empty, it will never become longer, no matter how many times we repeat it. In this scenario, we should throw an error.

Any function or method can throw an error as long as it is marked with the...

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Tech Concepts
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Programming languages
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Learning Swift Second Edition
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