Previews

At WWDC 2024, several sessions introduced new features and improvements related to previews in various contexts:

1. Xcode 16:

   • The session "What’s new in Xcode 16" introduced the previewable macro, which allows developers to attach it to property wrappers like state, enabling the creation of previews directly within a preview block without needing wrapper views. Additionally, the preview modifier API was introduced to facilitate sharing environment or data for previews, reducing duplicate code and enabling data caching. These enhancements make previews faster and more efficient, powered by a new execution engine. You can learn more about these improvements in the Improvements to Previews section.

2. SwiftData:

   • In the session "What’s new in SwiftData," the use of previews was discussed in the context of setting up a shared context for sample data. Developers can create a model configuration that stores data in memory only, making it easier to work on app views using Swift data queries. The previewable macro can also be used to create great previews for views that rely on models being passed to them. More details can be found in the Xcode previews section.

3. Quick Look for visionOS:

   • The session "What’s new in Quick Look for visionOS" introduced the PreviewApplication API, which provides more control over the Quick Look experience, including managing the lifecycle of previews and customizing editing options. This API allows for a more intuitive way to manage previewed files and enhances the 3D preview capabilities. For more information, see the PreviewApplication API section.

These sessions highlight the advancements in preview capabilities across different Apple platforms, making it easier for developers to create and manage previews efficiently.