add custom view and modifier

[betomoedano]

Custom SwiftUI views & modifiers

📚 Lesson: https://codewithbeto.dev/rnCourse/customSwiftUIViewsAndModifiers

This lesson adds a custom native module (modules/my-swift-ui-view) that exposes a SwiftUI view and modifiers to JS, then uses them alongside @expo/ui.

What we built

• Custom SwiftUI view — defined a ViewModifier view and exposed it from the module definition with ExpoUIView(...), so it renders inside an @expo/ui Host.
• Custom modifiers — mySwiftUiViewSwiftUIModifier (static border) and rotatingBorder (animated gradient border, iOS 17+).
• Lifecycle registration — modifiers are registered with ViewModifierRegistry.register(...) in OnCreate and torn down with unregister(...) in OnDestroy.
• Typed TS API — requireNativeView for the view and createModifier helpers for the modifiers, giving us type-safe props/params on the JS side.

How it's used

• Render our custom view inside the @expo/ui Host, passing children and an onTap event.
• Extend it with both built-in expo-ui modifiers (padding()) and our custom modifier (rotatingBorder).
• Apply our custom modifier to regular expo-ui views too — e.g. rotatingBorder on a Column.

A conceptual overview is covered in the lesson itself.