Concurrency

When we talk about Swift Concurrency, we also often mention Structured Concurrency. It's a fundamental part of async/await in Swift and helps us understand how Swift's latest improvements in concurrency work. Before async/await, we wrote our asynchronous methods using closures and Grand Central Dispatch (GCD). This worked well but often ...

In Swift Concurrency, we can use Task.sleep() and Task.yield() to let a specific task sleep or yield for a period of time. Both look and behave similarly, but there are a few significant differences to be aware of as Swift developers. Knowing these differences allows you to better understand when ...

Apple announced Swift 6 during WWDC 2024 as a major release of their programming language. It became first available in Xcode 16 and aims to create a fantastic development experience. Many of the latest more prominent features like async/await have been part of the road toward this major version bump ...

MainActor is a new attribute introduced in Swift 5.5 as a global actor providing an executor that performs its tasks on the main thread. When building apps, it's essential to perform UI updating tasks on the main thread, which can sometimes be challenging when using several background threads. Using the ...

URLSession allows you to perform network requests and becomes even more powerful with its async/await APIs. You can request data from a given URL and parse it into a decoded structure before displaying its data in a view. Popular frameworks like Alamofire aim to make it easier to perform requests, ...

Async await is part of the new structured concurrency changes that arrived in Swift 5.5 during WWDC 2021. Concurrency in Swift means allowing multiple pieces of code to run at the same time. This is a very simplified description, but it should give you an idea already how important concurrency ...

Concurrency-safe global variables help you prevent data races and allow you to solve strict-concurrency-related warnings. Since you can access global variables from any context, ensuring access is safe by removing mutability or conforming to Sendable is essential. As a developer, you must prevent data races since they can make your ...

Unit tests allow you to validate code written using the latest concurrency framework and async/await. While writing tests doesn't differ much from synchronous tests, there are a few crucial concepts to be aware of when validating asynchronous code. If you're new to async/await, I encourage you first to read Async ...

Actors ensure your code is executed on a specific thread, like the main or a background thread. They help you synchronize access to mutable states and prevent data races. However, developers commonly misunderstand how actors dispatch to threads in non-async contexts. It's an essential understanding to avoid unexpected crashes. Before ...

The @preconcurrency attribute is part of the tools that help you incrementally migrate to strict concurrency checking. When async/await was introduced by Apple, we were writing non-structured asynchronous code, mainly using closures. On our road to Swift 6, we must prepare our projects for strict concurrency checks done by the ...

Detached tasks allow you to create a new top-level task and disconnect from the current structured concurrency context. You could argue that using them results in unstructured concurrency since you're disconnecting potentially relevant tasks. While it sounds terrible to disconnect from structured concurrency, there are still examples of use cases ...