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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

Lost objects


It is a great idea to always keep strong reference cycles in mind, but if we are too aggressive with the use of weak and unowned references, we can run into the opposite problem, where an object is deleted before we intended it to be.

Between objects

With an object this will happen if all of the references to the object are weak or unowned. This won't be a fatal mistake if we use weak references, but if this happens with an unowned reference it will crash your program.

For example, let's look at the preceding example with an extra weak reference:

class SteeringWheel {
    weak var car: Car?
}
class Car {
    weak var steeringWheel: SteeringWheel!

    init(steeringWheel: SteeringWheel) {
        self.steeringWheel = steeringWheel
        steeringWheel.car = self
    }
}

let wheel = SteeringWheel()
let car = Car(steeringWheel: wheel)

This code is the same as the preceding one except that both the car property of SteeringWheel and the steeringWheel property of Car are weak. This means...

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