what is new uikit?

In the "What's new in UIKit" sessions at WWDC, several enhancements and new features were introduced for UIKit in iOS 18 and iOS 26. Here are some of the key updates:

1. Document Launch Experience: There is a redesigned launch experience for document-based apps, allowing for more control over launch views and support for template document creation. This helps in guiding users to create their first document while maintaining a great browsing experience.

2. Tabs and Sidebar Updates: Major updates to tabs and sidebars have been introduced, including a new syntax in SwiftUI for tab views and new APIs in UIKit to better describe app hierarchies to UITabBarController.

3. Fluid Transitions: New fluid transitions have been added, making animations more responsive and allowing users to interact with content without waiting for animations to finish.

4. SwiftUI and UIKit Interoperability: There are improvements in the interoperability between SwiftUI and UIKit, such as using SwiftUI animation types to animate UIKit views and adding UIKit gesture recognizers directly to SwiftUI hierarchies.

5. Automatic Trait Tracking: UIKit now supports automatic trait tracking, which simplifies handling changes in traits by automatically performing invalidations when traits change.

6. UIUpdateLink: A new feature in iOS 18, UIUpdateLink, makes it easier to implement complex animations that require periodic UI updates, similar to CADisplayLink.

7. New Design System: In iOS 26, a new design system was introduced with a material called Liquid Glass, which is translucent and dynamic, updating the look and feel of materials and controls across the system.

8. Architectural Improvements: UIKit now integrates Swift observation at its core, automatically tracking observable view references and invalidating views as needed.

For more detailed information, you can watch the sessions What's new in UIKit (2024) and What's new in UIKit (2025).