Hitches
Asked on 06/18/2025
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Hitches in app performance, particularly in animations, are a common topic discussed at WWDC. A hitch occurs when a frame stays visible on the screen for too long, delaying future frames and making animations appear less fluid. This can happen when UI updates take too long and miss the frame deadline, as explained in the session Optimize SwiftUI performance with Instruments.
To address hitches, Apple provides tools and techniques to diagnose and fix these issues. For instance, the XCT Hitch metric in Xcode 26 can be used to catch hitches during testing, as mentioned in the session What’s new in Xcode. This metric reports on hitch performance, such as the hitch time ratio, which represents the total amount of time your app was hitching over the duration of the measured portion of your test.
For more detailed information on hitches and how to address them, Apple recommends checking out the Tech Talk "Explore UI Animation, Hitches and the Render Loop."
Optimize SwiftUI performance with Instruments
Discover the new SwiftUI instrument. We’ll cover how SwiftUI updates views, how changes in your app’s data affect those updates, and how the new instrument helps you visualize those causes and effects. To get the most out of this session, we recommend being familiar with writing apps in SwiftUI.
What’s new in Xcode
Discover the latest productivity and performance advancements in Xcode 26. Learn how to leverage large language models in your development workflow. Explore editing and debugging enhancements, improved performance and testing tools, and Swift Build - the open-source build system engine used by Xcode.
Explore concurrency in SwiftUI
Discover how SwiftUI leverages Swift concurrency to build safe and responsive apps. Explore how SwiftUI uses the main actor by default and offloads work to other actors. Learn how to interpret concurrency annotations and manage async tasks with SwiftUI’s event loop for smooth animations and UI updates. You’ll leave knowing how to avoid data races and write code fearlessly.