iOS

Enro runs on iOS through Compose Multiplatform. Installation has two parts: the Swift app calls the generated installNavigationController extension at launch, and a Kotlin function returns the UIViewController that the Swift app displays.

Installation

From Swift

In the UIApplicationDelegate, call installNavigationController on the NavigationComponent object once at launch:

import UIKit
import shared

@main
class AppDelegate: UIResponder, UIApplicationDelegate {
    func application(
        _ application: UIApplication,
        didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
    ) -> Bool {
        MyComponent.shared.installNavigationController(
            application: application,
        )
        return true
    }
}

Kotlin/Native exports a Kotlin object to Swift with a shared accessor. Enro’s KSP processor generates the installNavigationController extension for the iOS target.

From Kotlin

Declare a function that returns a UIViewController. EnroUIViewController { } creates a Compose UIViewController and provides the root navigation context to the content:

fun MainViewController(): UIViewController = EnroUIViewController {
    val container = rememberNavigationContainer(
        backstack = backstackOf(Home.asInstance()),
    )
    NavigationDisplay(state = container)
}

In Swift, call MainViewController() and use the returned view controller as the root view controller. A UIKit app sets the view controller as the window’s root or adds the view controller as a child:

import UIKit
import shared

class ViewController: UIViewController {
    override func loadView() {
        let kotlinVc = MainViewControllerKt.MainViewController()
        addChild(kotlinVc)
        view = kotlinVc.view
        kotlinVc.didMove(toParent: self)
    }
}

A SwiftUI app wraps the Kotlin view controller in a UIViewControllerRepresentable.

UIViewController destinations

uiViewControllerDestination binds a key to a UIViewController. The metadata flag sets how Enro shows the view controller:

Flag	Shown
`SupportsCompose`	Embedded in the Enro container, like a Composable destination.
`SupportsPresent()`	Presented modally over the app.
`SupportsUINavigationView`	Pushed onto the `UINavigationController` that hosts the app.

// Plain UIKit, embedded in the Enro container.
@NavigationDestination(UIKitLabel::class)
val uiKitLabelDestination = uiViewControllerDestination<UIKitLabel>(
    metadata = { listOf(UIViewControllerDestination.SupportsCompose) },
    viewController = { instance ->
        UIViewController().apply {
            view.backgroundColor = UIColor.whiteColor
            val label = UILabel().apply {
                text = instance.key.text
                textAlignment = NSTextAlignmentCenter
                numberOfLines = 0
                setFrame(view.bounds)
                autoresizingMask = UIViewAutoresizingFlexibleWidth or UIViewAutoresizingFlexibleHeight
            }
            view.addSubview(label)
        }
    },
)

// Presented modally. The content is Compose, so it can close itself.
@NavigationDestination(PresentedViewController::class)
val presentedViewControllerDestination = uiViewControllerDestination<PresentedViewController>(
    metadata = { listOf(UIViewControllerDestination.SupportsPresent()) },
    viewController = {
        EnroUIViewController {
            val navigation = navigationHandle<PresentedViewController>()
            ViewControllerContent(
                title = "Presented modally",
                onClose = { navigation.close() },
            )
        }
    },
)

// Pushed onto the UINavigationController that hosts the app, which shows the
// system navigation bar and back button.
@NavigationDestination(PushedViewController::class)
val pushedViewControllerDestination = uiViewControllerDestination<PushedViewController>(
    metadata = { listOf(UIViewControllerDestination.SupportsUINavigationView) },
    viewController = {
        EnroUIViewController {
            val navigation = navigationHandle<PushedViewController>()
            ViewControllerContent(
                title = "Pushed onto the UINavigationController",
                onClose = { navigation.close() },
            )
        }
    },
)

SupportsUINavigationView requires the app’s root view controller to be inside a UINavigationController. The recipes Xcode project creates the UINavigationController in MainViewControllerView.swift.

See the UIViewController recipe.

What Enro provides on iOS

The system back gesture calls requestClose on the NavigationHandle of each destination that the back gesture removes.
The common API: NavigationKey, NavigationKey.WithResult<T>, navigationHandle<T>(), registerForNavigationResult, NavigationDisplay, scene strategies, plugins, decorators.

Notes

Enro does not use UINavigationController for Composable destinations. The containers inside an EnroUIViewController store the backstack. For a navigation bar, build the bar in Compose (the recipes app uses Material 3’s TopAppBar), or put the EnroUIViewController inside a UINavigationController and configure the bar in Swift.
Composable destinations behave on iOS as on the other platforms. A UIViewController is bound to a key as described in UIViewController destinations.

iOS