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  • Book Overview & Buying Swift 4 Programming Cookbook
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Swift 4 Programming Cookbook

Swift 4 Programming Cookbook

4.4 (5)
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Swift 4 Programming Cookbook

Swift 4 Programming Cookbook

4.4 (5)

Overview of this book

Swift 4 is an exciting, multi-platform, general-purpose programming language. Being open source, modern and easy to use has made Swift one of the fastest growing programming languages. If you interested in exploring it, then this book is what you need. The book begins with an introduction to the basic building blocks of Swift 4, its syntax and the functionalities of Swift constructs. Then, introduces you to Apple's Xcode 9 IDE and Swift Playgrounds, which provide an ideal platform to write, execute, and debug the codes thus initiating your development process. Next, you'll learn to bundle variables into tuples, set order to your data with an array, store key-value pairs with dictionaries and you'll learn how to use the property observers. Later, explore the decision-making and control structures in Swift and learn how to handle errors in Swift 4. Then you'll, examine the advanced features of Swift, generics and operators, and then explore the functionalities outside of the standard library, provided by frameworks such as Foundation and UIKit. Also, you'll explore advanced features of Swift Playgrounds. At the end of the book, you'll learn server-side programming aspect of Swift 4 and see how to run Swift on Linux and then investigate Vapor, one of the most popular server-side frameworks for Swift.
Table of Contents (15 chapters)
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Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Checking up front with guard


We have seen in previous recipes how we can use if statements to check Boolean expressions and unwrap optional values. It's a common use case to want to do some checks and conditional unwrapping at the beginning of a block of code, and then, only execute the subsequent code if everything is as expected. Often, this results in wrapping the whole block of code in an if statement:

if <#boolean check and unwrapping#> { 
    <#a block of code#> 
    <#that could be quite long#> 
} 

Swift has a better solution expressly for this purpose--the guard statement.

How to do it...

Let's imagine that we have some data that came from an external source, and we want to turn it into model objects that our code can understand and perhaps display it to the user:

  1. First, for the purpose of this example, let's create the data that can be from an external source; in this example, it is data on the planets of the solar system in the form of an array of dictionaries:
//...

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