flutter can't receive any RawKeyEvent on ios mobile

Question

This is my code

return RawKeyboardListener(
      focusNode: _listFocusNodeKeyListener[index],
      onKey: (event) {
        if (event.runtimeType == RawKeyUpEvent) {
          if (event.data.logicalKey == LogicalKeyboardKey.arrowLeft) {
            _prev(index);
          } else if (event.data.logicalKey == LogicalKeyboardKey.arrowRight) {
            _next(index);
          } else if (event.data.logicalKey == LogicalKeyboardKey.backspace) {
            if (_listControllerText[index].text.isEmpty) _prev(index);
          }
        }
      },
      child: Container(
        decoration: BoxDecoration(
          color: IMColors.bgSearchBar,
          borderRadius: BorderRadius.all(Radius.circular(10)),
        ),
        padding: EdgeInsets.only(top: 8),
        child: TextField(
          keyboardType: widget.keyboardType,
          inputFormatters: widget.digitsOnly
              ? <TextInputFormatter>[FilteringTextInputFormatter.digitsOnly]
              : null,
          maxLines: 1,
          maxLength: widget.length - index,
          controller: _listControllerText[index],
          focusNode: _listFocusNode[index],
          showCursor: true,
          cursorColor: widget.cursorColor,
          // maxLengthEnforcement: MaxLengthEnforcement.enforced,
          // autocorrect: false,
          textAlign: TextAlign.center,
          autofocus: widget.autofocus,
          style: widget.textStyle,
          expands: false,
          decoration: InputDecoration(
            border: InputBorder.none,
            // fillColor: widget.fillColor,
            // enabledBorder: null,
            // focusedBorder: null,
            counterText: '',
            // contentPadding: EdgeInsets.all(((widget.itemSize * 2) / 10)),
            // errorMaxLines: 1,
          ),
         
        ),
      ),
    );

in the onKey event mehtod,I can't receive any event while user is typing on ios,but it works on Android. And I found the ServicesBinding won't send any message abount keyEvnet on ios. The source code of _initKeyboard following:

void _initKeyboard() {
    _keyboard = HardwareKeyboard();
    _keyEventManager = KeyEventManager(_keyboard, RawKeyboard.instance);
    window.onKeyData = _keyEventManager.handleKeyData;
    SystemChannels.keyEvent.setMessageHandler(_keyEventManager.handleRawKeyMessage);
  }

The handleRawKeyMessage dont work while user is typing. Does anyone konw why and how to listen to the key events on ios?