Swift Concurrency by Example
Swift Concurrency by Example walks you through the many and varied ways of running concurrent code in Swift, including async/await, tasks, actors, and more.
THIS IS AN EARLY, INCOMPLETE EDITION OF THE BOOK.
Many more chapters will be added in the next four to six weeks, along with extra examples and more detail in the existing chapters, plus downloadable Xcode projects and illustrations to help make concepts clearer.
The Swift Evolution proposals behind these changes continue to evolve, and you should make sure you download the latest Swift 5.5 development snapshot before trying the examples contained here.
Thank you for your patience! If you spot any problems with the text, please email paul@hackingwithswift.com.
Introduction
- This stuff is hard
- How to follow this guide
- Concurrency vs parallelism
- Understanding threads and queues
- Main thread and main queue: what’s the difference?
Async/await
- What is a synchronous function?
- What is an asynchronous function?
- How to create and call an async function
- How to call async throwing functions
- What calls the first async function?
- How to call an async function using async let
- What’s the difference between await and async let?
- Why can’t we call async functions using async var?
- How to use continuations to convert completion handlers into async functions
- How to create continuations that can throw errors
- How to store continuations to be resumed later
- How to fix the error “async call in a function that does not support concurrency”
Sequences and streams
- What’s the difference between Sequence, AsyncSequence, and AsyncStream?
- How to loop over an AsyncSequence using for await
- How to manipulate an AsyncSequence using map(), filter(), and more
- How to create a custom AsyncSequence
- How to convert an AsyncSequence into a Sequence
Tasks and task groups
- What are tasks and task groups?
- How to create and run a task
- What’s the difference between a task and a detached task?
- How to get a Result from a task
- How to control the priority of a task
- Understanding how priority escalation works
- How to cancel a Task
- How to make a task sleep
Actors
