FlutterViewController Not Visible in Audio Unit Extensions

Goal

Make it possible to develop Audio Unit Extensions with Flutter.

Problem

Until now we were not able to show a Flutter view controller within an Audio Unit Extensions

Solution

We need support from the Flutter team, to help us to make FlutterViewController work as part of an Audio Unit Extension. Here are the steps to reproduce the issue:

1. Check out and prepare the repository

git clone [email protected]:gatzsche/flutter-audio-unit-extension-experiments.git
cd flutter-audio-unit-extension-experiments/
cd flutter_auv3_unit/
flutter pub get

2. Build and run the plugin container app

• Open flutter_auv3_unit/ios/Runner.xcworkspace/ with Xcode.

• Select target Runner

  

• Run Runner on a chosen simulator

  

3. Build and run the plugin host app

• Open AUV3Host/AUv3Host/AUv3Host.xcodeproj/ with Xcode

• Select iOSAUv3Host as target

  

• Run iOSAUv3Host on the same simulator the plugin container app was executed.

  

4. Debug the audio unit using the plugin host app

• Switch back to flutter_auv3_unit/ios/Runner.xcworkspace/ Xcode project

• Select audio unit target FlutterAUV3

  

• Run the plugin on the same simulator as before

  

• Select AUv3Host as the app to run

  

• Within AUv3Host: select the Instruments tab

  

• Select Flutter Example Audio Unit

  

• Wait three seconds

• Click on View

  

5. Here is the bug

• Normally the Flutter default app should be shown
• But you see only the red background of the FlutterViewController

6. Hints

• The commandline output shows that flutter is executed and also the widget tree is built. Probably the rendering does not work properly.