Flutter/Flutter.h' file not found のがiOSビルド時に頻発するときの対応

問題

• ビルドしようとうすると以下のエラーが出る。
• Flutter/Flutter.h' file not found

al error: 'Flutter/Flutter.h' file not found
    #import <Flutter/Flutter.h>
            ^~~~~~~~~~~~~~~~~~~
    1 error generated.
    Command CompileSwift failed with a nonzero exit code
    note: Using new build system
    note: Building targets in parallel
    note: Planning build

対応

• https://www.yuukinishiyama.com/2021/01/16/flutter-fatal-error-flutter-flutter-h-file-not-found%E3%81%8C%E9%80%A3%E7%99%BA%E3%81%99%E3%82%8B/
• 以下の対応で再度ビルドしたらいけた

rm ios/Flutter/Flutter.podspec
flutter clean