Fix: iOS background worker

[armandsLa]

There is an issue with how HomeWidgetBackgroundWorker uses async/await in its iOS implementation. Currently, the run method returns immediately, before the platform channel can be initialized and the Flutter callback performed.

I've refactored the HomeWidgetBackgroundWorker with a proper async/await implementation. Now, the run method will return only after the interactivity callback in Flutter has been executed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (1b0456f) to head (af3be43).

Additional details and impacted files

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  Coverage   100.00%   100.00%           
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  Files            3         3           
  Lines          104       104           
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  Hits           104       104           

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[armandsLa]

I've been testing this PR over the weekend and can confirm that it resolves the issue where widgets might not reload with new data after saveWidgetData and updateWidget are called from the interactivity callback. This issue only occurred when the interactivity callback took a bit longer to execute.

To better understand the issue, the sequence of actions was as follows:

1. Call HomeWidgetBackgroundWorker.run from an iOS widget.
2. Receive the interactivity callback in Flutter.
3. Execute a task that takes longer to complete.
4. Call saveWidgetData with the new data.
5. Immediately call updateWidget thereafter.

In this scenario, the widget would reload, but with the previously saved data, not the one saved in step 4. I still have no idea why this is happening. My best guess is that returning .result() from an Intent before data gets saved halts the internal synchronization of user defaults.

[Oleksandr32]

hi @armandsLa, I have tried your solution and it works.
But now I see this warning:

channel sent a message from native to Flutter on a non-platform thread. Platform channel messages must be sent on the platform thread. Failure to do so may result in data loss or crashes, and must be fixed in the plugin or application code creating that channel. See https://docs.flutter.dev/platform-integration/platform-channels#channels-and-platform-threading for more information.

[armandsLa]

@Oleksandr32 Thank you for reporting this issue. I was calling HomeWidgetBackgroundWorker from the main thread, so I never encountered this error. I have now added Dispatch to ensure it is safe to call HomeWidgetBackgroundWorker from any thread. Please let me know if this resolves the issue.

[Oleksandr32]

@armandsLa The issue has been resolved. Thanks

[armandsLa]

@ABausG will you be able to review and merge this PR?

[ABausG]

Yes sorry!! Will do it after FlutterCon

[ABausG]

LGTM - had to read a bit about async / await works on Swift. Thanks for this. currently looking into the failing android pipeline, but I should get this landed and released this weekend!