I was using the MaterialStateProperty which is deprecated. So instead I updated it to WidgetStateProperty. But then I get this error from my pipeline (build failed):

Error (Xcode): lib/ui/switch_button.dart Error: Type 'WidgetStateProperty' not found.

This is my code:

final WidgetStateProperty<Icon?> thumbIcon =
      WidgetStateProperty.resolveWith<Icon?>(
    (Set<WidgetState> states) {
      if (states.contains(WidgetState.selected)) {
        return const Icon(Icons.check);
      }
      return const Icon(Icons.close);
    },
  );

Or should I try to update Xcode maybe?

I saw a similar post about this where a guy said to use the deprecated MaterialStateProperty or is this not the same issue?

Similar issue: Flutter Undefined name ‘WidgetStateProperty’