hangs
Asked on 2025-10-28
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It seems like you're interested in understanding how to handle app hangs, particularly in the context of Swift concurrency. At WWDC, Apple presented several sessions that address this topic, focusing on how to use Swift concurrency to improve app performance and responsiveness.
One relevant session is "Code-along: Elevate an app with Swift concurrency" (wwdc2025-270). In this session, they discuss how to handle expensive processing tasks that can cause app hangs by offloading work to background threads. For example, they demonstrate how to use Swift concurrency to move image processing off the main thread to prevent UI hangs during scrolling. You can learn more about this in the chapter on Running tasks on a background thread.
Another session, "Embracing Swift concurrency" (wwdc2025-268), explains how to use concurrency to prevent UI hangs when performing tasks like decoding large images. They emphasize the importance of not blocking the main thread and using asynchronous tasks to keep the UI responsive. This is covered in the chapter on Asynchronous tasks.
If you're interested in analyzing and diagnosing hangs, the session "What’s new in Xcode 16" (wwdc2024-10135) introduces the flame graph tool in Instruments, which can help identify performance bottlenecks that may lead to hangs. This is discussed in the chapter on Meet the flame graph.
These sessions provide valuable insights into using Swift concurrency to improve app performance and prevent hangs.
Code-along: Elevate an app with Swift concurrency
Learn how to optimize your app’s user experience with Swift concurrency as we update an existing sample app. We’ll start with a main-actor app, then gradually introduce asynchronous code as we need to. We’ll use tasks to optimize code running on the main actor, and discover how to parallelize code by offloading work to the background. We’ll explore what data-race safety provides, and work through interpreting and fixing data-race safety errors. Finally, we’ll show how you can make the most out of structured concurrency in the context of an app.
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 Xcode 16
Discover the latest productivity and performance improvements in Xcode 16. Learn about enhancements to code completion, diagnostics, and Xcode Previews. Find out more about updates in builds and explore improvements in debugging and Instruments.