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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

Multi-pattern catch clauses

In the previous section, we had code that looked like this:

do {
    try myTeam.addPlayer(player:("David", "Ortiz", 34))
} catch PlayerNumberError.NumberTooHigh(let description) { 
    print("Error: \(description)")
} catch PlayerNumberError.NumberTooLow(let description) {
    print("Error: \(description)")
} catch PlayerNumberError.NumberAlreadyAssigned { 
    print("Error: Number already assigned")
} catch {
    print("Error: Unknown Error")
}

You will notice that the catch clause for the PlayerNmberError.NumberTooHigh and PlayerNumberError.NumberTooLow errors contains duplicate code. When you are developing, it is always good to find a way to eliminate duplicate code like this. However, prior to Swift 5.3, we did not have a choice. Swift introduced multi-pattern catch clauses with SE-0276 in Swift 5.3 to help reduce duplicate code like this. Let's take a look at this by rewriting...

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