hjemmesidekongen/expo-swiftui

Expo SwiftUI

Expo Modules API is Swift-first. A Module subclass with a Definition() body exposes functions, constants, and views to JavaScript — no Objective-C bridging or .m files required.

Module Structure

Define the module, name it, and register any functions and views in definition(). The Name() call must match the string used in requireNativeModule() on the JS side.

SwiftUI View Integration

Expo views subclass ExpoView (not UIView). To host a SwiftUI view, wrap it in a UIHostingController and add the hosting controller's view as a subview. Override layoutSubviews() to keep the hosted view's frame in sync with bounds.

Props and Events

Props are declared with Prop in the module Definition() and applied to the ExpoView subclass. Events use @EventDispatcher on the view class and are registered with Events() in the definition. Fire them by calling the dispatcher with a plain dictionary payload.

Accessing iOS APIs

Call any iOS SDK directly from the module or view. APIs requiring permissions need a config plugin that adds the NSUsageDescription key to Info.plist — never edit Info.plist manually since expo prebuild regenerates it.

Lifecycle

ExpoView lifecycle: didMoveToWindow(), willMove(toSuperview:), and SwiftUI .onAppear / .onDisappear inside the hosted view. Module-level lifecycle uses OnCreate and OnDestroy in the definition body.

Native Navigation Integration

To push native UIKit screens from within a module, access the root view controller via appContext?.utilities?.currentViewController(). Avoid doing this in props — use a module function that JS calls explicitly.

See references/process.md for full Swift module code, UIHostingController setup, config plugin patterns, testing native modules, debugging on-device, and anti-patterns.