Book Image

Mastering Swift 3

Book Image

Mastering Swift 3

Overview of this book

Swift is the definitive language of Apple development today. It’s a vital part of any iOS and OS X developer’s skillset, helping them to build the most impressive and popular apps on the App Store—the sort of apps that are essential to iPhone and iPad users every day. With version 3.0, the Swift team have added new features to improve the development experience—making it easier to get the results you want and customers expect. Inside, you’ll find the key features of Swift 3.0 and quickly learn how to use the newest updates to your development advantage. From Objective-C interoperability to ARC, to closures and concurrency, this advanced Swift guide will develop your expertise and make you more fluent in this vital programming language. We give you in-depth knowledge of some of the most sophisticated elements of Swift development including protocol extensions, error-handling, design patterns, and concurrency, and guide you on how to use and apply them in your own projects. You'll see how even the most challenging design patterns and programming techniques can be used to write cleaner code and to build more performant iOS and OS X applications. By the end of this book, you’ll have a handle on effective design patterns and techniques, which means you’ll soon be writing better iOS and OS X applications with a new level of sophistication and control.
Table of Contents (23 chapters)
Mastering Swift 3
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Free Chapter
1
Taking the First Steps with Swift
2
Learning About Variables, Constants, Strings, and Operators

An introduction to closures


Closures are self-contained blocks of code that can be passed around and used throughout our application. We can think of an Int type as a type that stores an integer and a String type as a type that stores a string. In this context, a closure can be thought of as a type that contains a block of code. What this means is that we can assign closures to a variable, pass them as arguments to functions, and also return them from functions.

Closures have the ability to capture and store references to any variable or constant from the context in which they were defined. This is known as closing over the variables or constants, and the best thing is, for the most part, Swift will handle the memory management for us. The only exception is when we create a strong reference cycle, and we will look at how to resolve this in the Creating strong reference cycles with closures section of this chapter.

Closures in Swift are similar to blocks in Objective-C; however, closures in...