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Mastering Swift 3

You're reading from   Mastering Swift 3 Build incredible apps for iOS and OS X

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Product type Paperback
Published in Oct 2016
Publisher Packt
ISBN-13 9781786466129
Length 392 pages
Edition 1st Edition
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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 (18) Chapters Close

Preface 1. Taking the First Steps with Swift FREE CHAPTER 2. Learning About Variables, Constants, Strings, and Operators 3. Using Swift Collections and the Tuple Type 4. Control Flow and Functions 5. Classes and Structures 6. Using Protocols and Protocol Extensions 7. Protocol-Oriented Design 8. Writing Safer Code with Availability and Error Handling 9. Custom Subscripting 10. Using Optional Types 11. Working with Generics 12. Working with Closures 13. Using Mix and Match 14. Concurrency and Parallelism in Swift 15. Swift Formatting and Style Guide 16. Swifts Core Libraries 17. Adopting Design Patterns in Swift

Calculated subscripts


While the preceding example is very similar to using the stored properties in a class or structure, we can also use subscripts in a similar manner to the computed properties. Let's see how to do this:

struct MathTable { 
    var num: Int 
    
    subscript(index: Int) -> Int { 
        return num * index 
    } 
} 

In the preceding example, we used an array as the backend storage mechanism for the subscript. In this example, we use the value of the subscript to calculate the return value. We would use this subscript as follows:

var table = MathTable(num: 5) 
print(table[4]) 

This example will display the calculated value of 5 (the number defined in the initialization) multiplied by 4 (the subscript value), which is equal to 20.

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