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Learning Swift Second Edition

Learning Swift Second Edition

By : Andrew J Wagner
5 (1)
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Learning Swift Second Edition

Learning Swift Second Edition

5 (1)
By: Andrew J Wagner

Overview of this book

Swift is Apple’s new programming language and the future of iOS and OS X app development. It is a high-performance language that feels like a modern scripting language. On the surface, Swift is easy to jump into, but it has complex underpinnings that are critical to becoming proficient at turning an idea into reality. This book is an approachable, step-by-step introduction into programming with Swift for everyone. It begins by giving you an overview of the key features through practical examples and progresses to more advanced topics that help differentiate the proficient developers from the mediocre ones. It covers important concepts such as Variables, Optionals, Closures, Generics, and Memory Management. Mixed in with those concepts, it also helps you learn the art of programming such as maintainability, useful design patterns, and resources to further your knowledge. This all culminates in writing a basic iOS app that will get you well on your way to turning your own app ideas into reality.
Table of Contents (14 chapters)
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13
Index

Extending generics


The two main generics that we will probably want to extend are arrays and dictionaries. These are the two most prominent containers provided by Swift and are used in virtually every app. Extending a generic type is simple once you understand that an extension itself does not need to be generic.

Adding methods to all forms of a generic

Knowing that an array is declared as struct Array<Element>, your first instinct to extend an array might look something similar to this:

extension Array<Element> { // Use of undeclared type 'Element'
    // ...
}

However, as you can see, you would get an error. Instead, you can simply leave out the placeholder specification and still use the Element placeholder inside your implementations. Your other instinct might be to declare Element as a placeholder for your individual methods:

extension Array {
    func someMethod<Element>(element: Element) {
        // ...
    }
}

This is more dangerous because the compiler doesn't detect...

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