feat: migrate to SceneDelegate

[artus9033]

Summary:

This PR introduces a migration from the now-deprecated iOS AppDelegate to SceneDelegate, as well as the changes to React Native code that will migrate to APIs allowing it to work fine with the SceneDelegate approach. There are two primary goals of this API:

• feature: ability for users to leverage resizable windows feature on iPadOS in RN apps
• stay ahead of the incoming changes, since AppDelegate is scheduled to be deleted in future releases of iOS

The changes are additive to RN and maintain backwards compatibility, but require user-space modifications to RN apps that want to migrate from AppDelegate to the scene lifecycle.

What changed

Bootstrap (Libraries/AppDelegate)

• RCTSceneDelegate - introduced fast integration point for subclassing in the user-space SceneDelegate base class (counterpart to RCTAppDelegate)
• RCTReactNativeFactory - SceneDelegate entrypoints via UISceneConnectionOptions
• RCTAppDelegate retained; deprecation wording updated to point scene apps to RCTSceneDelegate

Utilities (React/Base)

• RCTGetActiveReactNativeFactory() - resolve factory from SceneDelegate or AppDelegate
• RCTKeyWindow() - iOS 13–14 fallback for scene-based apps
• RCTIsSceneDelegateApp() - dual-path linking detection

Linking (Libraries/LinkingIOS)

• SceneDelegate class methods on RCTLinkingManager; AppDelegate methods retained for non-scene apps

Core modules

• RCTDeviceInfo - refresh cached getConstants() on orientation/frame/content-size changes
• NativeDeviceInfo JS - remove stale constants caching
• RCTDevLoadingView - layout/dismiss fixes for scene window resizing

Sample apps

• RNTester (default): RCTSceneDelegate; AppDelegate handles push notifications
• RNTester (AppDelegate) scheme: legacy path via RNTESTER_USE_APPDELEGATE
• HelloWorld: SceneDelegate default; legacy bootstrap in AppDelegate.legacy.swift

The RFC documenting the details is available here.

Example usage:

An example entrypoint using the added RCTSceneDelegate (imported from React_RCTAppDelegate) is:

internal import Expo
import React
import React_RCTAppDelegate
import ReactAppDependencyProvider
import UIKit

class SceneDelegate: RCTSceneDelegate {
  override func scene(
    _ scene: UIScene,
    willConnectTo session: UISceneSession,
    options connectionOptions: UIScene.ConnectionOptions
  ) {
    moduleName = "main"
    dependencyProvider = RCTAppDependencyProvider()
    automaticallyLoadReactNativeWindow = false

    guard let windowScene = scene as? UIWindowScene else {
      return
    }

    let delegate = ReactNativeDelegate()
    delegate.dependencyProvider = RCTAppDependencyProvider()
    reactNativeFactory = ExpoReactNativeFactory(delegate: delegate)

    window = UIWindow(windowScene: windowScene)

    reactNativeFactory?.startReactNative(
      withModuleName: moduleName ?? "main",
      in: window,
      initialProperties: initialProps,
      connectionOptions: connectionOptions
    )
  }
}

class ReactNativeDelegate: ExpoReactNativeFactoryDelegate {
  override func bundleURL() -> URL? {
#if DEBUG
    return RCTBundleURLProvider.sharedSettings().jsBundleURL(forBundleRoot: ".expo/.virtual-metro-entry")
#else
    return Bundle.main.url(forResource: "main", withExtension: "jsbundle")
#endif
  }
}

Follow-ups:

After merging this PR, the AppDelegate will be deprecated, but still available. After a future de-integration of AppDelegate, packages/react-native/Libraries/AppDelegate and contained files should be renamed.

Additional information

One capability that can be leveraged with the SceneDelegate on iPadOS is multi-window (multi-instance) support, which would cause all sorts of problems in the current React Native core and 3p libraries' designs. Therefore, enabling this capability is currently unsupported by React Native and to enforce this, a warning message like the one below would be printed provided this capability had been enabled:

Changelog:

[IOS] [ADDED] - SceneDelegate support with backwards compatibility to AppDelegate-only approaches
[IOS] [ADDED] - RCTSceneDelegate, RCTGetActiveReactNativeFactory(), and RCTReactNativeFactory SceneDelegate entrypoints
[IOS] [ADDED] - RCTLinkingManager SceneDelegate lifecycle methods (AppDelegate path retained)
[IOS] [CHANGED] - DeviceInfo to update the value returned by getConstants upon frame change
[IOS] [CHANGED] - RCTDevLoadingView layout for scene window resizing
[IOS] [ADDED] - additional scheme: RNTester (AppDelegate), allowing to run RNTester with AppDelegate infrastructure
[IOS] [ADDED] - print warning from RCTReactNativeFactory if UIApplicationSceneManifest.UIApplicationSupportsMultipleScenes in Info.plist is set to true, which is unsupported by RN to prevent bugs due to simultaneously running multiple instances of an app

Test Plan:

• Evaluate that RNTester works properly (default RNTester SceneDelegate and RNTester (AppDelegate) schemes)
• Verify HelloWorld SceneDelegate bootstrap; deep links and iPadOS window resize / Dimensions updates

RNTester

ScreenRecording_07-13-2026.12-26-27_1.mov

HelloWorld

ScreenRecording_07-13-2026.13-15-08_1.mov

[cipolleschi]

Hi @artus9033, thanks for working on this.
The PR is very detailed and well prepared.

I think we can simplify some assumption to make it smaller and more maintainable.
I left some comments in the PR. Could you address them?

[cipolleschi]

if it is not supported, can't we crash? I think we should raise an exception. A warning in console is very easy to miss. Perhaps we can add a compiler flag that transforms the crash in a warning, but at least users will have to do it themselves and hopefully they'll know what they are doing.
WDYT?

[artus9033]

I agree, we can make this an assertion. I think the option to opt out with a compiler flag is sensible. I do not foresee use cases when users would enable this, because even if they would do so, internal React Native components that use NSNotificationCenter would cross-talk across scenes.

[cipolleschi]

not a fan of the subclassing. Can't we move away from the subclassing approach and show the users how to use the RCTReactNativeFactory directly? What are they going to miss if they don't use this subclass?

[artus9033]

It's purely a utility to reduce the amount of code the users would need to write. I don't strongly suggest this approach, we can instead document what they need to add and drop this helper.

[cipolleschi]

This can be removed. It is not possible to disable New Arch

[cipolleschi]

We probably need to update the website with these. I would not add the RCTSceneDelegate at all.

[cipolleschi]

nit: I typically prefer not to have negation logic. I find it easier to read the code.

Suggested change

	if (!RCTIsSceneDelegateApp()) {
	[RCTLinkingManager postNotificationWithURL:URL];
	return YES;
	}
	return YES;
	return NO;
	if (RCTIsSceneDelegateApp()) {
	return NO;
	}
	[RCTLinkingManager postNotificationWithURL:URL];
	return YES;

[cipolleschi]

this can go

[cipolleschi]

can we move these js changes to a different PR? They are unrelated from the SceneDelegate.

[cipolleschi]

not sure it is worth to complicate RNTester like this.
Also, I don't want to show a pattern to the user that is not the best one.

I would probably simplify the PR and drop the AppDelegate completely.

[cipolleschi]

what would it be if we do not extend the RCTSceneDelegate?

[cipolleschi]

same as above, let's simplify and get rid of this.