Book Image

Swift 4 Programming Cookbook

Book Image

Swift 4 Programming Cookbook

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 (9 chapters)

Bailing out with fatalError and precondition

It's comforting to think that, in the code you write, everything will always happen as expected, and your program can handle any eventuality. However, sometimes things can go wrong, really wrong; a situation can arise that you know is possible, but don't expect to ever happen, and the programs should terminate if it does. Swift has a way to define these situations, and in this recipe, we will look at two of them: fatalError and precondition.

Getting ready

Let's reuse our example from the previous recipe; we have an object that can be used to classify movie reviews based on how many stars out of ten the review gave the movie. However, let's simplify its use, and...