[iOS] Migrate FlutterLaunchEngine to Swift by cbracken · Pull Request #185151 · flutter/flutter

cbracken · 2026-04-16T14:45:17Z

Migrates FlutterLaunchEngine from Objective-C to Swift. This also renames the Swift class to LaunchEngine. The Obj-C name remains FlutterLaunchEngine.

Also adds more comprehensive tests.

Issue: #175878

Pre-launch Checklist

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flutter-dashboard · 2026-04-16T14:45:22Z

It looks like this pull request may not have tests. Please make sure to add tests or get an explicit test exemption before merging.

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Code Review

This pull request migrates the FlutterLaunchEngine from Objective-C to Swift, renaming it to LaunchEngine while maintaining Objective-C compatibility. The changes include updating the build configuration and replacing the existing Objective-C tests with Swift unit tests. Feedback highlights a missing import in FlutterViewController.mm necessary for compilation and a recommendation to mark the LaunchEngine class as final per the Swift style guide.

Migrates `FlutterLaunchEngine` from Objective-C to Swift. This also renames the Swift class to `LaunchEngine`. The Obj-C name remains `FlutterLaunchEngine`. Also adds more comprehensive tests.

cbracken · 2026-04-16T15:03:52Z

It looks like this pull request may not have tests. Please make sure to add tests or get an explicit test exemption before merging.

Whoops. I suspect when I added Swift support, I didn't update cocoon or the bot or wherever with a regex for swift tests?

/cc @jtmcdole is the github test check stuff in cocoon? Happy to fix the code when I find some time, if I can remember where it is.

cbracken · 2026-04-16T15:32:32Z

+@objc(FlutterLaunchEngine)
+public final class LaunchEngine: NSObject {
+  private var didTakeEngine = false
+  private var _engine: FlutterEngine?


This is mostly just a straight port of existing code, but I've got a followup that consolidates these into a state enum with .uninitialized, .created(FlutterEngine), .taken. On the fence as to whether that's any better. Curious to hear opinions on that. If we want to take this one, then I can send that out later to see what people think.

state enum is great

hellohuanlin · 2026-04-16T16:53:59Z

+@objc(FlutterLaunchEngine)
+public final class LaunchEngine: NSObject {
+  private var didTakeEngine = false
+  private var _engine: FlutterEngine?


state enum is great

jtmcdole · 2026-04-16T17:05:00Z

/cc @jtmcdole is the github test check stuff in cocoon? Happy to fix the code when I find some time, if I can remember where it is.

Yes! flutter/cocoon has the test checker.

https://github.com/flutter/cocoon/blob/1f542c36145bf37cfdea294310784e968568aeb7/app_dart/lib/src/request_handlers/github/webhook_subscription.dart#L606-L647

I actually think its the "_isAnEngineTest"

…#185151)

flutter/flutter@31f1802...8e8a194 2026-04-17 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Fix ImageInfo.isCloneOf to correctly compare scale values (fixes #184626) (#184643)" (flutter/flutter#185203) 2026-04-17 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Roll Fuchsia Test Scripts from R2EllDf4DgBXVNuiN... to dQ4PjIJB5kZFU8Y32... (#185192)" (flutter/flutter#185199) 2026-04-17 chris@bracken.jp [iOS] Migrate FlutterLaunchEngine to Swift (flutter/flutter#185151) 2026-04-17 116356835+AbdeMohlbi@users.noreply.github.com Remove unused `FlutterRunArguments.java` file (flutter/flutter#184160) 2026-04-17 engine-flutter-autoroll@skia.org Roll Fuchsia Test Scripts from R2EllDf4DgBXVNuiN... to dQ4PjIJB5kZFU8Y32... (flutter/flutter#185192) 2026-04-17 pewpewstol@gmail.com [Impeller] Fix morphology filter asymmetric dilation/erosion (flutter/flutter#184913) 2026-04-17 nate.w5687@gmail.com `AnimationStyle` methods (flutter/flutter#182333) 2026-04-17 karan@solvejet.net Fix _scheduleSystemFontsUpdate assertion during non-idle scheduler phase (flutter/flutter#184332) 2026-04-17 154381524+flutteractionsbot@users.noreply.github.com Revert "Unpin sdk package dependencies" (flutter/flutter#185186) 2026-04-16 116356835+AbdeMohlbi@users.noreply.github.com Clarify why the `child` is nullable in `AnimatedTransitionBuilder` (flutter/flutter#182995) 2026-04-16 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from IdBT8fSMYrYSip65j... to di3JdYrdE9OFu8Iyl... (flutter/flutter#185173) 2026-04-16 1063596+reidbaker@users.noreply.github.com Add dart_skills_lint to dev/tool with test and update readme instructions for new skills authors (flutter/flutter#185033) 2026-04-16 flar@google.com [Impeller] Provide std::optional getter for stroke property (flutter/flutter#185112) 2026-04-16 katelovett@google.com Validate itemExtent with geometry in RenderSliverFixedExtentBoxAdaptor (flutter/flutter#185159) 2026-04-16 152433210+mozammal-hossain@users.noreply.github.com [iOS] Clarify provisioning profile error instructions (flutter/flutter#184051) 2026-04-16 bkonyi@google.com [Widget Preview] Fix flaky integration test timeout during flutter clean (flutter/flutter#184991) 2026-04-16 engine-flutter-autoroll@skia.org Roll Dart SDK from fbddcbe0cd96 to 7c2564c18770 (2 revisions) (flutter/flutter#185143) 2026-04-16 sigurdm@google.com Unpin sdk package dependencies (flutter/flutter#184821) 2026-04-16 68919043+Istiak-Ahmed78@users.noreply.github.com Fix ImageInfo.isCloneOf to correctly compare scale values (fixes #184626) (flutter/flutter#184643) 2026-04-16 engine-flutter-autoroll@skia.org Roll Skia from 391cdbe3ffe9 to d8415c5d7b91 (2 revisions) (flutter/flutter#185141) 2026-04-16 154381524+flutteractionsbot@users.noreply.github.com Sync CHANGELOG.md from stable (flutter/flutter#185166) 2026-04-16 154381524+flutteractionsbot@users.noreply.github.com Revert "Move widget_preview_scaffold into pub workspace" (flutter/flutter#185164) 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 boetger@google.com,stuartmorgan@google.com 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

…r#11523) flutter/flutter@31f1802...8e8a194 2026-04-17 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Fix ImageInfo.isCloneOf to correctly compare scale values (fixes #184626) (#184643)" (flutter/flutter#185203) 2026-04-17 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Roll Fuchsia Test Scripts from R2EllDf4DgBXVNuiN... to dQ4PjIJB5kZFU8Y32... (#185192)" (flutter/flutter#185199) 2026-04-17 chris@bracken.jp [iOS] Migrate FlutterLaunchEngine to Swift (flutter/flutter#185151) 2026-04-17 116356835+AbdeMohlbi@users.noreply.github.com Remove unused `FlutterRunArguments.java` file (flutter/flutter#184160) 2026-04-17 engine-flutter-autoroll@skia.org Roll Fuchsia Test Scripts from R2EllDf4DgBXVNuiN... to dQ4PjIJB5kZFU8Y32... (flutter/flutter#185192) 2026-04-17 pewpewstol@gmail.com [Impeller] Fix morphology filter asymmetric dilation/erosion (flutter/flutter#184913) 2026-04-17 nate.w5687@gmail.com `AnimationStyle` methods (flutter/flutter#182333) 2026-04-17 karan@solvejet.net Fix _scheduleSystemFontsUpdate assertion during non-idle scheduler phase (flutter/flutter#184332) 2026-04-17 154381524+flutteractionsbot@users.noreply.github.com Revert "Unpin sdk package dependencies" (flutter/flutter#185186) 2026-04-16 116356835+AbdeMohlbi@users.noreply.github.com Clarify why the `child` is nullable in `AnimatedTransitionBuilder` (flutter/flutter#182995) 2026-04-16 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from IdBT8fSMYrYSip65j... to di3JdYrdE9OFu8Iyl... (flutter/flutter#185173) 2026-04-16 1063596+reidbaker@users.noreply.github.com Add dart_skills_lint to dev/tool with test and update readme instructions for new skills authors (flutter/flutter#185033) 2026-04-16 flar@google.com [Impeller] Provide std::optional getter for stroke property (flutter/flutter#185112) 2026-04-16 katelovett@google.com Validate itemExtent with geometry in RenderSliverFixedExtentBoxAdaptor (flutter/flutter#185159) 2026-04-16 152433210+mozammal-hossain@users.noreply.github.com [iOS] Clarify provisioning profile error instructions (flutter/flutter#184051) 2026-04-16 bkonyi@google.com [Widget Preview] Fix flaky integration test timeout during flutter clean (flutter/flutter#184991) 2026-04-16 engine-flutter-autoroll@skia.org Roll Dart SDK from fbddcbe0cd96 to 7c2564c18770 (2 revisions) (flutter/flutter#185143) 2026-04-16 sigurdm@google.com Unpin sdk package dependencies (flutter/flutter#184821) 2026-04-16 68919043+Istiak-Ahmed78@users.noreply.github.com Fix ImageInfo.isCloneOf to correctly compare scale values (fixes #184626) (flutter/flutter#184643) 2026-04-16 engine-flutter-autoroll@skia.org Roll Skia from 391cdbe3ffe9 to d8415c5d7b91 (2 revisions) (flutter/flutter#185141) 2026-04-16 154381524+flutteractionsbot@users.noreply.github.com Sync CHANGELOG.md from stable (flutter/flutter#185166) 2026-04-16 154381524+flutteractionsbot@users.noreply.github.com Revert "Move widget_preview_scaffold into pub workspace" (flutter/flutter#185164) 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 boetger@google.com,stuartmorgan@google.com 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

cbracken requested a review from a team as a code owner April 16, 2026 14:45

github-actions Bot added platform-ios iOS applications specifically engine flutter/engine related. See also e: labels. team-ios Owned by iOS platform team labels Apr 16, 2026

cbracken force-pushed the swift-launchengine branch from 9127b0c to b9a21b1 Compare April 16, 2026 14:46

gemini-code-assist Bot reviewed Apr 16, 2026

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Comment thread engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterViewController.mm

Comment thread engine/src/flutter/shell/platform/darwin/ios/framework/Source/LaunchEngine.swift Outdated

cbracken force-pushed the swift-launchengine branch from b9a21b1 to e0ee6dd Compare April 16, 2026 14:53

[iOS] Migrate FlutterLaunchEngine to Swift

19a0af0

Migrates `FlutterLaunchEngine` from Objective-C to Swift. This also renames the Swift class to `LaunchEngine`. The Obj-C name remains `FlutterLaunchEngine`. Also adds more comprehensive tests.

cbracken force-pushed the swift-launchengine branch from e0ee6dd to 19a0af0 Compare April 16, 2026 14:58

cbracken requested a review from hellohuanlin April 16, 2026 14:59

cbracken commented Apr 16, 2026

View reviewed changes

hellohuanlin approved these changes Apr 16, 2026

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jmagman added the CICD Run CI/CD label Apr 16, 2026

Merge branch 'master' into swift-launchengine

9b48ec4

github-actions Bot removed the CICD Run CI/CD label Apr 16, 2026

cbracken enabled auto-merge April 16, 2026 22:34

Merge branch 'master' into swift-launchengine

2384896

Renzo-Olivares added the CICD Run CI/CD label Apr 17, 2026

cbracken added this pull request to the merge queue Apr 17, 2026

cbracken mentioned this pull request Apr 17, 2026

[iOS] Recognise Swift tests as tests in the GitHub test check bot #185194

Closed

Merged via the queue into flutter:master with commit 02da4c6 Apr 17, 2026
194 checks passed

cbracken deleted the swift-launchengine branch April 17, 2026 08:00

engine-flutter-autoroll mentioned this pull request Apr 17, 2026

Roll Flutter from 31f1802cb859 to 8e8a194923dc (22 revisions) flutter/packages#11523

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engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Apr 17, 2026

02da4c69f [iOS] Migrate FlutterLaunchEngine to Swift (flutter/flutter…

a0b9c4f

…#185151)

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[iOS] Migrate FlutterLaunchEngine to Swift#185151

[iOS] Migrate FlutterLaunchEngine to Swift#185151
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