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Mastering Swift 5

You're reading from   Mastering Swift 5 Deep dive into the latest edition of the Swift programming language

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Product type Paperback
Published in Apr 2019
Publisher Packt
ISBN-13 9781789139860
Length 370 pages
Edition 5th Edition
Languages
Tools
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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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Table of Contents (20) Chapters Close

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

The availability attribute

Using the latest SDK gives us access to all the latest features for the platform that we are developing for; however, there are times when we want to also target older platforms. Swift allows us to use the availability attribute to safely wrap code to run only when the correct version of the operating system is available. This availability was first introduced in Swift 2.

The availability attribute is only available when we use Swift on Apple platforms.

The availability blocks essentially let us, if we are running the specified version of the operating system or higher, run this code or otherwise run some other code. There are two ways in which we can use the availability attribute. The first way allows us to execute a specific block of code that can be used with an if or a guard statement. The second way allows us to mark a method or type as available...

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