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Swift Cookbook

You're reading from   Swift Cookbook Proven recipes for developing robust iOS applications with Swift 5.9

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Product type Paperback
Published in Jun 2024
Publisher Packt
ISBN-13 9781803239583
Length 422 pages
Edition 3rd Edition
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Authors (4):
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Chris Barker Chris Barker
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Chris Barker
Daniel Bolella Daniel Bolella
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Daniel Bolella
Nathan Lawlor Nathan Lawlor
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Nathan Lawlor
Keith Moon Keith Moon
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Keith Moon
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Toc

Table of Contents (15) Chapters Close

Preface 1. Chapter 1: Swift Fundamentals 2. Chapter 2: Mastering the Building Blocks FREE CHAPTER 3. Chapter 3: Data Wrangling with Swift 4. Chapter 4: Generics, Operators, and Nested Types 5. Chapter 5: Beyond the Standard Library 6. Chapter 6: Understanding Concurrency in Swift 7. Chapter 7: Building iOS Apps with UIKit 8. Chapter 8: Building iOS Apps with SwiftUI 9. Chapter 9: Getting to Grips with Combine 10. Chapter 10: Using CoreML and Vision in Swift 11. Chapter 11: Immersive Swift with ARKit and Augmented Reality 12. Chapter 12: Visualizing Data with Swift Charts 13. Index 14. Other Books You May Enjoy

Leveraging DispatchGroups

In the previous recipe, we looked into using a private serial queue to keep our app responsive by moving long-running operations off the main queue. In this recipe, we will break our operations down into smaller, independent blocks and place them on a concurrent queue.

Getting ready

We are going to build on the app we improved in the last recipe, which is an app that will produce a PDF photo book from a collection of photos. You can get the code for this app at https://github.com/PacktPublishing/Swift-Cookbook-Third-Edition/tree/main/Chapter%206 and choose the PhotobookCreator_DispatchGroups folder.

Open the project in Xcode and navigate to the PhotoCollectionViewController.swift file.

How to do it...

In the last recipe, we saw how dispatch queues operate on a FIFO policy. GCD will execute a block from the top of the queue and remove it from the queue when it has finished executing. The number of blocks that GCD will allow to execute at the...

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