iOS 26 SDK Deadline - How React Native and Flutter Teams Must Migrate Now

Apple's official App Store requirements page states it plainly: after April 28, 2026, every new submission and every update must target the iOS 26 SDK and be built with Xcode 26. Miss the deadline and App Store Connect rejects your binary on upload. No grace period. No manual review override. Your users stop getting updates until you ship a compliant build.

For teams shipping pure Swift or Objective-C apps, this is a straightforward Xcode upgrade. For React Native and Flutter teams, the iOS 26 SDK introduces a breaking change to the app lifecycle that requires code-level migration, not just a toolchain swap.

What changed in iOS 26 SDK that breaks cross-platform apps

The core change is the deprecation of UIApplicationDelegate as the primary lifecycle entry point. iOS 26 standardises on the UIScene lifecycle, which Apple first introduced in iOS 13 but left optional until now. Apps that still rely on the old AppDelegate-only pattern compile without error under Xcode 26, but fail validation at submission time because the SDK enforces scene-based lifecycle as mandatory for new binaries.

Both React Native and Flutter historically generated an AppDelegate that bypassed UIScene entirely. That pattern is now a hard submission blocker. The migration touches the iOS host project, not the Dart or JavaScript layer, but it still requires careful coordination with your framework version.

React Native migration - what version you need and what to change

React Native 0.79, released in March 2026, ships with a UIScene-compatible AppDelegate template. If your project is on 0.78 or earlier, the generated AppDelegate.mm will not satisfy iOS 26 SDK requirements. Upgrade is non-negotiable.

1. Upgrade to RN 0.79 or later. Run npx react-native upgrade and follow the interactive diff. Pay attention to the iOS directory changes. The new template introduces SceneDelegate.mm and a revised AppDelegate.mm that calls into RCTAppDelegate's scene lifecycle methods.
2. Update Info.plist with UIApplicationSceneManifest. The iOS 26 SDK requires an UIApplicationSceneManifest key in your app's Info.plist. Add a scene configuration block that references your SceneDelegate class. Without this key, App Store Connect rejects the binary with error ITMS-90424.
3. Audit native modules for AppDelegate hooks. Any native module that implements application:didFinishLaunchingWithOptions: directly must be updated to use the new RN 0.79 module API that hooks into scene lifecycle events. Common offenders: react-native-firebase (Analytics), react-native-push-notification, and any module that manually sets rootViewController.
4. Test with Xcode 26 simulators before submission. Build with the iOS 26 SDK target explicitly set. The simulator will surface scene lifecycle issues that won't appear when targeting iOS 17 with the old SDK.
5. Verify archive and distribution settings. In your Xcode project, confirm that IPHONEOS_DEPLOYMENT_TARGET is set appropriately and that the base SDK resolves to iOS 26. CI pipelines using xcodebuild need the -sdk iphoneos26 flag.

The UIScene migration is not optional polish. It is a binary gate. A build that passes all your tests and works perfectly on device will still be rejected at upload if it targets the wrong SDK.

Flutter migration - Flutter 3.32 and the lifecycle hook changes

Flutter's engine team shipped UIScene support in Flutter 3.32, released alongside Xcode 26 in early April 2026. If your project runs Flutter 3.30 or earlier, the generated iOS runner template does not include a SceneDelegate and will fail App Store submission after April 28.

• Upgrade Flutter to 3.32+. Run flutter upgrade in your project. Then run flutter create --platforms=ios . in your project root to regenerate the iOS runner files. This overwrites AppDelegate.swift, Runner.xcodeproj, and adds SceneDelegate.swift. Back up any custom AppDelegate code before running this.
• Migrate custom AppDelegate code to SceneDelegate. If you push custom code into AppDelegate.swift (common for Firebase setup, deep link handling, or push notification registration), that code needs to move to the appropriate UIScene delegate methods. scene(_:willConnectTo:options:) replaces application(_:didFinishLaunchingWithOptions:) for most initialisation tasks.
• Check flutter_local_notifications and firebase_messaging. Both packages had breaking updates in their April 2026 releases specifically to handle the UIScene lifecycle. Update to flutter_local_notifications 18.0+ and firebase_messaging 15.2+. Older versions route notification taps through AppDelegate methods that no longer fire reliably under UIScene.
• Validate with flutter build ipa --release. This produces the IPA locally and surfaces SDK compliance errors before you waste an App Store Connect upload attempt. Watch for deprecation warnings tagged as errors under the iOS 26 SDK - Apple promoted several previously-soft deprecations to hard errors in this release.

Common mistakes that will cost you the deadline

Teams running into trouble almost always make one of three errors. Each is avoidable.

• Upgrading only the framework, not Xcode. React Native 0.79 and Flutter 3.32 generate correct code, but if your CI machine runs Xcode 15 or Xcode 16, the archive targets the wrong SDK regardless of what your project files say. Xcode 26 must be the build tool. Update your CI runner or switch to a cloud build service that supports it.
• Assuming the app works because it runs on device. A sideloaded build does not go through App Store validation. Your app can function perfectly while failing SDK compliance checks that only run at upload time. Always do a TestFlight submission as a dry run before the production release.
• Missing third-party plugin updates. The UIScene change is framework-wide. Any plugin that registers for iOS lifecycle callbacks needs an update. Run flutter pub outdated or npm outdated and check each native-bridge plugin's changelog for "iOS 26" or "UIScene" mentions. If a plugin hasn't shipped an update by now, open an issue and consider a temporary fork.

The two days you have left

April 28 is not a soft target. App Store Connect already shows the warning banner on any submission attempt from a non-compliant binary. If your app is in active development with a pending release, your submission window is effectively today and tomorrow.

Prioritize the iOS native layer changes first since they block submission entirely. JavaScript and Dart logic changes can follow in a subsequent release. Ship a compliant binary to TestFlight today, confirm it passes processing, then push to production. One compliant build in App Store Connect before the deadline keeps your update pipeline open. You can iterate on features after.

Building on a tight deadline is our specialty

At SARVAYA, we've helped multiple product teams push through exactly this kind of platform-forced migration under time pressure. Whether your app is built on React Native, Flutter, or a custom native wrapper, we can audit your iOS project, apply the UIScene migration, and get you a compliant build before the deadline closes. See our recent mobile project work or reach out directly if you need a same-day assessment.