what is swift concurrency
Asked on 06/23/2025
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Swift Concurrency is a model introduced to help developers write concurrent code more easily and safely in Swift. It allows code to perform multiple tasks simultaneously, which can improve the responsiveness of apps, especially when dealing with operations like network requests or processing large data sets. The concurrency model in Swift is designed to make concurrent code easier to write correctly by making the introduction of concurrency explicit and identifying shared data across concurrent tasks. This helps in preventing data races, which are common errors in concurrent programming.
Key features of Swift Concurrency include:
- Tasks: The fundamental unit of concurrency in Swift, representing an independent concurrent execution context. Tasks are lightweight and can be created in large numbers.
- Actors: Used for protecting mutable state and ensuring data isolation, which helps in preventing data races.
- Async/Await: A syntax for writing asynchronous code that is easier to read and maintain.
- Main Actor: A concept that allows code to run on the main thread by default, which is useful for UI-related tasks.
Swift Concurrency also includes tools for identifying performance issues and potential data races at compile time, making it safer to introduce concurrency into your app without fear of creating hard-to-fix bugs.
For more detailed information, you can refer to the session Embracing Swift concurrency from WWDC 2025.
Embracing Swift concurrency
Join us to learn the core Swift concurrency concepts. Concurrency helps you improve app responsiveness and performance, and Swift is designed to make asynchronous and concurrent code easier to write correctly. We’ll cover the steps you need to take an app through from single-threaded to concurrent. We’ll also help you determine how and when to make the best use of Swift concurrency features – whether it’s making your code more asynchronous, moving it to the background, or sharing data across concurrent tasks.
What’s new in Swift
Join us for an update on Swift. We’ll briefly go through a history of Swift over the past decade, and show you how the community has grown through workgroups, expanded the package ecosystem, and increased platform support. We’ll introduce you to a new language mode that achieves data-race safety by default, and a language subset that lets you run Swift on highly constrained systems. We’ll also explore some language updates including noncopyable types, typed throws, and improved C++ interoperability.
A Swift Tour: Explore Swift’s features and design
Learn the essential features and design philosophy of the Swift programming language. We’ll explore how to model data, handle errors, use protocols, write concurrent code, and more while building up a Swift package that has a library, an HTTP server, and a command line client. Whether you’re just beginning your Swift journey or have been with us from the start, this talk will help you get the most out of the language.