uikit-interop

name: uikit-interop description: Use when bridging SwiftUI and UIKit with representables, UIHostingController, UIHostingConfiguration, or incremental adoption.

UIKit Interop

Review and write interop code for correct bridging between SwiftUI and UIKit in both directions.

Responsibility

Owns: UIViewRepresentable (makeUIView, updateUIView, Coordinator), UIViewControllerRepresentable (makeUIViewController, updateUIViewController), UIHostingController, UIHostingConfiguration (iOS 16+), context.animate {} for coordinated animations (iOS 17+), incremental adoption patterns.

Does NOT own: Pure SwiftUI views (swiftui-patterns skill), pure UIKit views (uikit-fundamentals skill), Core Animation bridging (core-animation skill).

Core Principles

1. UIViewRepresentable is a struct. makeUIView creates once, updateUIView syncs state. Never recreate the UIView in updateUIView.
2. Coordinator for delegates. Use the Coordinator class for UIKit delegate callbacks. The coordinator holds a reference to the parent representable via the binding, not a strong reference to the SwiftUI view.
3. context.animate {} for coordinated animations. On iOS 17+, use context.animate { } in updateUIView to coordinate UIKit animations with SwiftUI transitions.
4. UIHostingController for SwiftUI in UIKit. Embed SwiftUI views in UIKit via UIHostingController. Add as a child view controller — don't just add its view.
5. UIHostingConfiguration for cells. Use UIHostingConfiguration { SwiftUIView() } for collection/table view cells (iOS 16+). No need for a hosting controller per cell.
6. Incremental adoption. Start with leaf views (buttons, inputs) when adopting SwiftUI in a UIKit app. Start with UIKit wrappers for missing components when adopting UIKit in a SwiftUI app.
7. sizingOptions for hosting controllers. Set .intrinsicContentSize on UIHostingController to let Auto Layout size it correctly.

References

• references/uikit-interop-patterns.md — Representable protocols, hosting, coordinated animations, adoption patterns