Book Image

Swift High Performance

By : Kostiantyn Koval
Book Image

Swift High Performance

By: Kostiantyn Koval

Overview of this book

Swift is one of the most popular and powerful programming languages for building iOS and Mac OS applications, and continues to evolve with new features and capabilities. Swift is considered a replacement to Objective-C and has performance advantages over Objective-C and Python. Swift adopts safe programming patterns and adds modern features to make programming easier, more flexible, and more fun. Develop Swift and discover best practices that allow you to build solid applications and optimize their performance. First, a few of performance characteristics of Swift will be explained. You will implement new tools available in Swift, including Playgrounds and REPL. These will improve your code efficiency, enable you to analyse Swift code, and enhance performance. Next, the importance of building solid applications using multithreading concurrency and multi-core device architecture is covered, before moving on to best practices and techniques that you should utilize when building high performance applications, such as concurrency and lazy-loading. Finally, you will explore the underlying structure of Swift further, and learn how to disassemble and compile Swift code.
Table of Contents (15 chapters)
Swift High Performance
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Lazy collections and evaluation


Another very interesting place where we could perform work lazily is collections and sequences. We store many elements in them, and sometimes, performing an operation such as filter or map would take a lot of time and may be unnecessary.

Before we dig into the details, let's first check out a small example to see why working lazily with a collection is so useful. We have a collection. We want to perform an operation such as mapping on it, and get one or a few elements from the result. Here is how we would implement it using an array:

let numbers = Array(1...1_000_000) 
let doubledNumbers = numbers.map { $0 * 2 }
doubledNumbers.last

When we call the map method on the numbers array, it applies it to every element in the array and returns the new mapped array. As a result, we get a new doubledNumbers array. Our map { $0 * 2 } closure is called as many times as there are elements in the array; in our case, it is 1,000,000 times. But we need only the last element...