Fucking Approachable Swift Concurrency

A no-bullshit guide to understanding Swift concurrency. Learn async/await, actors, Sendable, and MainActor with simple mental models.

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About

Swift concurrency can be confusing. This site distills the best resources into clear, approachable mental models that anyone can understand.

In the tradition of fuckingblocksyntax.com and fuckingifcaseletsyntax.com.

Topics Covered

• Async/Await - Suspension vs blocking, and why it matters
• Tasks - Managing async work with Task and TaskGroup
• Isolation - The core mental model for Swift concurrency (MainActor, actors, nonisolated)
• Sendable - What can safely cross isolation boundaries
• Isolation Inheritance - How isolation flows through your code
• Common Mistakes - And how to avoid them

Languages

Available in 10 languages: English, Spanish, Portuguese (BR & PT), Arabic, Korean, Japanese, Chinese (Simplified & Traditional), Russian and Turkish.

Development

This site is built with Eleventy.

Prerequisites

• mise (for managing Node.js and pnpm)

Setup

mise install
pnpm install

Development Server

pnpm dev

Then open http://localhost:8080/ in your browser.

Build

pnpm build

Credits

Much of this guide is distilled from Matt Massicotte's excellent work on Swift concurrency.

License

MIT License - see LICENSE.md

Contributors ✨

Thanks goes to these wonderful people (emoji key):

Akshay 🖋

Peter's Path 🖋

Sébastien Stormacq 🖋

Ertan 📖

Vikram Kriplaney 🖋

This project follows the all-contributors specification. Contributions of any kind welcome!