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Add state restoration for UIScene migration #176305
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Add state restoration for UIScene migration #176305
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Code Review
This pull request adds support for state restoration in iOS apps using UIScene. It introduces new UISceneDelegate methods to save and restore state, which are then handled in FlutterSceneLifeCycle. The implementation includes a check against the app's modification date to prevent restoring state into an incompatible app version. The changes are accompanied by new devicelab tests, native UI tests, and unit tests to verify the functionality for both migrated and unmigrated apps. My review includes suggestions to improve performance by reducing file system access within loops and to enhance test coverage.
dev/integration_tests/ios_add2app_uiscene/native/UITests-StateRestoration.swift
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engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterSceneLifeCycle.mm
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engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterSceneLifeCycle.mm
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| NSUserActivity* state = [delegate stateRestorationActivityForScene:mockScene]; | ||
| XCTAssertEqual(state.userInfo[restorationId], mockData); | ||
| XCTAssertEqual(state.activityType, configName); |
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This test is missing an assertion to verify that the modification date (kRestorationStateAppModificationKey) is added to the userInfo. To add this assertion, you'll also need to mock -[FlutterPluginSceneLifeCycleDelegate lastAppModificationTime] or the underlying NSBundle calls, similar to how it's done in testSceneRestoreInteractionStateWithUserActivity. This will make the test more robust.
engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterSceneLifeCycle.mm
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engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterSceneLifeCycle.mm
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| // Restores state per FlutterViewController. | ||
| NSDictionary<NSString*, id>* userInfo = stateRestorationActivity.userInfo; | ||
| [self updateEnginesInScene:scene]; | ||
| for (FlutterEngine* engine in [_engines allObjects]) { |
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Hmm, when does UIKit call this method? I would assume this is called when the app is re-lauched so you'd have to restore _engines first?
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We sync'd offline, but scene:restoreInteractionStateWithUserActivity happens after storyboard initialization so the engine will have connected during
flutter/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngine.mm
Lines 278 to 293 in 23a9ce3
| - (void)sceneWillConnect:(NSNotification*)notification API_AVAILABLE(ios(13.0)) { | |
| UIScene* scene = notification.object; | |
| if (!FlutterSharedApplication.application.supportsMultipleScenes) { | |
| // Since there is only one scene, we can assume that the FlutterEngine is within this scene and | |
| // register it to the scene. | |
| // The FlutterEngine needs to be registered with the scene when the scene connects in order for | |
| // plugins to receive the `scene:willConnectToSession:options` event. | |
| // If we want to support multi-window on iPad later, we may need to add a way for deveopers to | |
| // register their FlutterEngine to the scene manually during this event. | |
| FlutterPluginSceneLifeCycleDelegate* sceneLifeCycleDelegate = | |
| [FlutterPluginSceneLifeCycleDelegate fromScene:scene]; | |
| if (sceneLifeCycleDelegate != nil) { | |
| return [sceneLifeCycleDelegate engine:self receivedConnectNotificationFor:scene]; | |
| } | |
| } | |
| } |
engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterSceneLifeCycle.mm
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engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterSceneLifeCycle.mm
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| for (FlutterEngine* engine in [_engines allObjects]) { | ||
| UIViewController* vc = (UIViewController*)engine.viewController; | ||
| NSString* restorationId = vc.restorationIdentifier; |
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Without multiview support FlutterViewControllers can't share the same engine?
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Right, only 1 FlutterViewController per FlutterEngine right now
flutter/flutter@5c0c9e9...908012d 2025-10-05 [email protected] Roll Skia from 5479115ef5bf to 1fd0ca1f2120 (1 revision) (flutter/flutter#176541) 2025-10-05 [email protected] Roll Fuchsia Linux SDK from oWcBvgdpdlGvaqiDg... to Zm6K_3gP3VCaMy9rH... (flutter/flutter#176538) 2025-10-05 [email protected] Roll Dart SDK from 53aeaeb2454c to 016a8c0045fd (1 revision) (flutter/flutter#176531) 2025-10-04 [email protected] Roll Skia from f316de3d47b4 to 5479115ef5bf (4 revisions) (flutter/flutter#176529) 2025-10-04 [email protected] Roll Dart SDK from 9bc52df78b67 to 53aeaeb2454c (1 revision) (flutter/flutter#176525) 2025-10-04 [email protected] Roll Fuchsia Linux SDK from HUhTcRn-LUXa2Salu... to oWcBvgdpdlGvaqiDg... (flutter/flutter#176515) 2025-10-04 [email protected] Fix TextFormField does not inherit local InputDecorationTheme (flutter/flutter#176397) 2025-10-04 [email protected] Roll Dart SDK from 0009748aed50 to 9bc52df78b67 (4 revisions) (flutter/flutter#176506) 2025-10-04 [email protected] Roll Skia from 9cda1a2050c4 to f316de3d47b4 (2 revisions) (flutter/flutter#176504) 2025-10-04 [email protected] fix: support older git (ubuntu 22.04) in content hash (flutter/flutter#176321) 2025-10-04 [email protected] Roll Skia from a454242c3934 to 9cda1a2050c4 (2 revisions) (flutter/flutter#176499) 2025-10-03 [email protected] [material/menu_anchor.dart] Check for reserved padding updates on layout delegate. (flutter/flutter#176457) 2025-10-03 [email protected] Roll Skia from b842026480e0 to a454242c3934 (3 revisions) (flutter/flutter#176484) 2025-10-03 [email protected] Starts updating the DEPS in preupload. (flutter/flutter#176485) 2025-10-03 [email protected] Align flutter dependencies with ones coming from dart. (flutter/flutter#176475) 2025-10-03 [email protected] fix: delay exiting microbenchmark (flutter/flutter#176477) 2025-10-03 [email protected] Add state restoration for UIScene migration (flutter/flutter#176305) 2025-10-03 [email protected] Fix Voiceover traversal for OutlinedButton.icon (flutter/flutter#175810) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC [email protected] on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md
When an iOS app migrates to UIScene, the application events for handling state restoration are no longer called by UIKit. Instead, scene events in the SceneDelegate must be used. This PR adds support for handling state restoration in UIScene while still maintaining support for unmigrated apps, as well. Fixes flutter#174402. ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [x] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement]. - [x] I signed the [CLA]. - [x] I listed at least one issue that this PR fixes in the description above. - [x] I updated/added relevant documentation (doc comments with `///`). - [x] I added new tests to check the change I am making, or this PR is [test-exempt]. - [x] I followed the [breaking change policy] and added [Data Driven Fixes] where supported. - [x] All existing and new tests are passing. If you need help, consider asking for advice on the #hackers-new channel on [Discord]. **Note**: The Flutter team is currently trialing the use of [Gemini Code Assist for GitHub](https://developers.google.com/gemini-code-assist/docs/review-github-code). Comments from the `gemini-code-assist` bot should not be taken as authoritative feedback from the Flutter team. If you find its comments useful you can update your code accordingly, but if you are unsure or disagree with the feedback, please feel free to wait for a Flutter team member's review for guidance on which automated comments should be addressed. <!-- Links --> [Contributor Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview [Tree Hygiene]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md [test-exempt]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests [Flutter Style Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md [Features we expect every widget to implement]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement [CLA]: https://cla.developers.google.com/ [flutter/tests]: https://github.com/flutter/tests [breaking change policy]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes [Discord]: https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md [Data Driven Fixes]: https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md
When an iOS app migrates to UIScene, the application events for handling state restoration are no longer called by UIKit. Instead, scene events in the SceneDelegate must be used. This PR adds support for handling state restoration in UIScene while still maintaining support for unmigrated apps, as well. Fixes flutter#174402. ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [x] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement]. - [x] I signed the [CLA]. - [x] I listed at least one issue that this PR fixes in the description above. - [x] I updated/added relevant documentation (doc comments with `///`). - [x] I added new tests to check the change I am making, or this PR is [test-exempt]. - [x] I followed the [breaking change policy] and added [Data Driven Fixes] where supported. - [x] All existing and new tests are passing. If you need help, consider asking for advice on the #hackers-new channel on [Discord]. **Note**: The Flutter team is currently trialing the use of [Gemini Code Assist for GitHub](https://developers.google.com/gemini-code-assist/docs/review-github-code). Comments from the `gemini-code-assist` bot should not be taken as authoritative feedback from the Flutter team. If you find its comments useful you can update your code accordingly, but if you are unsure or disagree with the feedback, please feel free to wait for a Flutter team member's review for guidance on which automated comments should be addressed. <!-- Links --> [Contributor Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview [Tree Hygiene]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md [test-exempt]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests [Flutter Style Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md [Features we expect every widget to implement]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement [CLA]: https://cla.developers.google.com/ [flutter/tests]: https://github.com/flutter/tests [breaking change policy]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes [Discord]: https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md [Data Driven Fixes]: https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md
When an iOS app migrates to UIScene, the application events for handling state restoration are no longer called by UIKit. Instead, scene events in the SceneDelegate must be used. This PR adds support for handling state restoration in UIScene while still maintaining support for unmigrated apps, as well. Fixes flutter#174402. ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [x] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement]. - [x] I signed the [CLA]. - [x] I listed at least one issue that this PR fixes in the description above. - [x] I updated/added relevant documentation (doc comments with `///`). - [x] I added new tests to check the change I am making, or this PR is [test-exempt]. - [x] I followed the [breaking change policy] and added [Data Driven Fixes] where supported. - [x] All existing and new tests are passing. If you need help, consider asking for advice on the #hackers-new channel on [Discord]. **Note**: The Flutter team is currently trialing the use of [Gemini Code Assist for GitHub](https://developers.google.com/gemini-code-assist/docs/review-github-code). Comments from the `gemini-code-assist` bot should not be taken as authoritative feedback from the Flutter team. If you find its comments useful you can update your code accordingly, but if you are unsure or disagree with the feedback, please feel free to wait for a Flutter team member's review for guidance on which automated comments should be addressed. <!-- Links --> [Contributor Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview [Tree Hygiene]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md [test-exempt]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests [Flutter Style Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md [Features we expect every widget to implement]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement [CLA]: https://cla.developers.google.com/ [flutter/tests]: https://github.com/flutter/tests [breaking change policy]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes [Discord]: https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md [Data Driven Fixes]: https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md
When an iOS app migrates to UIScene, the application events for handling state restoration are no longer called by UIKit. Instead, scene events in the SceneDelegate must be used. This PR adds support for handling state restoration in UIScene while still maintaining support for unmigrated apps, as well.
Fixes #174402.
Pre-launch Checklist
///).If you need help, consider asking for advice on the #hackers-new channel on Discord.
Note: The Flutter team is currently trialing the use of Gemini Code Assist for GitHub. Comments from the
gemini-code-assistbot should not be taken as authoritative feedback from the Flutter team. If you find its comments useful you can update your code accordingly, but if you are unsure or disagree with the feedback, please feel free to wait for a Flutter team member's review for guidance on which automated comments should be addressed.