TextFormField(
        spellCheckConfiguration: SpellCheckConfiguration(
          misspelledSelectionColor: Colors.red,
          spellCheckService: DefaultSpellCheckService(),
        ),
        autovalidateMode: AutovalidateMode.onUserInteraction,
        controller: descriptionController,
        textInputAction: TextInputAction.done,
        keyboardType: TextInputType.multiline,
        maxLines: 4,
        maxLength: 250,
        maxLengthEnforcement: MaxLengthEnforcement.enforced,
        onSaved: (newValue) =>
            campaignPostViewController.setDescription(newValue!),
        style: TextStyle(color: ColorConstants.white, fontSize: 14.sp),
        focusNode: campaignPostViewController.descriptionFocusNode,
        decoration: const InputDecoration(
          hintText: 'your hint',
          hintStyle: TextStyle(
            color: Colors.white,
            fontSize: 16,
            fontWeight: FontWeight.w500,
          ),
          enabledBorder: UnderlineInputBorder(
            borderSide: BorderSide(color: Colors.transparent),
          ),
          focusedBorder: UnderlineInputBorder(
            borderSide: BorderSide(color: Colors.transparent),
          ),
          contentPadding: EdgeInsets.all(0),
        ),
      )

The Spell check configuration is not working in iOS

Tried with CupertinoTextfield and normal Textfield.
expected output is with the red curvy underline for the mispelled words on typing on the field.