#Preview

Preview in Xcode 16

In the session titled "What’s new in Xcode 16," several enhancements to the preview system were introduced. The previewable macro allows developers to attach it to property wrappers like state, enabling direct use within a preview block without needing to write wrapper views. This simplifies the process of creating live UI previews with minimal code. Additionally, the preview modifier API helps share environment or data across previews, reducing duplicate code and enabling data caching for improved performance. These updates are part of a broader effort to enhance the speed and efficiency of previews, powered by advances in the compiler and build system.

Quick Look for visionOS

The session "What’s new in Quick Look for visionOS" introduced the preview application API, which gives apps more control over the Quick Look experience. This includes managing the lifecycle of previews and customizing the display of 3D content. Notably, the API allows for surface snapping, enabling 3D models to be positioned on horizontal surfaces like tables or floors. This feature enhances the spatial media preview capabilities of apps, making it easier to create immersive experiences.

SwiftData Previews

In "What’s new in SwiftData," the session discussed setting up shared contexts for previews using model containers. This approach allows for in-memory data storage, making it easier to work with sample data in SwiftUI views. The previewable macro can also be used to create effective previews for views that rely on models being passed to them, enhancing the development process by providing realistic data scenarios.

Relevant Sessions

• What’s new in Xcode 16 (Improvements to Previews)
• What’s new in Quick Look for visionOS (PreviewApplication API)
• What’s new in SwiftData (Xcode previews)