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Mastering Swift 5.3

You're reading from   Mastering Swift 5.3 Upgrade your knowledge and become an expert in the latest version of the Swift programming language

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Product type Paperback
Published in Nov 2020
Publisher Packt
ISBN-13 9781800562158
Length 418 pages
Edition 6th Edition
Languages
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Author (1):
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Jon Hoffman Jon Hoffman
Author Profile Icon Jon Hoffman
Jon Hoffman
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Toc

Table of Contents (23) Chapters Close

Preface 1. Taking the First Steps with Swift 2. Swift Documentation and Installing Swift FREE CHAPTER 3. Learning about Variables, Constants, Strings, and Operators 4. Optional Types 5. Using Swift Collections 6. Control Flow 7. Functions 8. Classes, Structures, and Protocols 9. Protocols and Protocol Extensions 10. Protocol-Oriented Design 11. Generics 12. Error Handling and Availability 13. Custom Subscripting 14. Working with Closures 15. Advanced and Custom Operators 16. Concurrency and Parallelism in Swift 17. Custom Value Types 18. Memory Management 19. Swift Formatting and Style Guide 20. Adopting Design Patterns in Swift 21. Other Books You May Enjoy
22. Index

Simple closures

We will begin by creating a very simple closure that does not accept any arguments and does not return any value. All it does is print Hello World to the console. Let's look at the following code:

let clos1 = { () -> Void in
    print("Hello World")
}

In this example, we create a closure and assign it to the clos1 constant. Since there are no parameters defined between the parentheses, this closure will not accept any parameters. Also, the return type is defined as Void; therefore, this closure will not return any value. The body of the closure contains one line, which prints Hello World to the console.

There are many ways to use closures; in this example, all we want to do is execute it. We can execute the closure as follows:

clos1()

After executing the closure, we will see that Hello World is printed to the console. At this point, closures may not seem that useful, but as we get further along in this chapter, we will see how...

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