1、在你下载的Flutter根目录中用终端执行
flutter upgrade
2、cd进去自己开发的flutter代码路径执行
flutter clean
Cleaning Xcode workspace... 3.8s
Deleting build... 110ms
Deleting .dart_tool... 7ms
Deleting .android... 6ms
Deleting .ios... 47ms
3、执行
flutter packages get
4、执行
flutter build ios
5、最后进入Xcode中执行command+B,flutter.h文件的报错就会消失了