Flutter-iOS构建错误：重复符号'_main'

Question

由于符号重复，我无法在模拟器上构建iOS。参见下文：

duplicate symbol '_main' in:
    /Users/sthomas/Library/Developer/Xcode/DerivedData/Runner-ftvesijaqdysdeapgqmlgudlnwhc/Build/Intermediates.noindex/Runner.build/Debug-iphonesimulator/Runner.build/Objects-normal/x86_64/main.o
    /Users/sthomas/Library/Developer/Xcode/DerivedData/Runner-ftvesijaqdysdeapgqmlgudlnwhc/Build/Intermediates.noindex/Runner.build/Debug-iphonesimulator/Runner.build/Objects-normal/x86_64/AppDelegate-e55f8212d335a630f4374f2941350df53ffd306ad05b58b05b854d66b221c95e.o
ld: 1 duplicate symbol for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

我尝试删除派生数据：

rm -rf  ~/Library/Developer/Xcode/DerivedData

以及以下内容：

  cd ios/
  pod cache clean --all
  pod deintegrate --verbose
  pod setup --verbose
  pod install --verbose
  flutter clean

有什么想法吗？

编辑：添加了编译源的屏幕截图。