This code is working for laptop keyboard delete key press. But it’s not printing backspace pressed in iphone and android clear icon pressed . How to achieve this?
Enter the first three digits of the 4-digit PIN incorrectly.
Press the X button on the keyboard to clear the previous field.
Observe that the focus remains on the current field (PIN), even after pressing the X button multiple times, preventing the user from easily correcting the mobile number
Pressing the X button should move the focus to the previous field and clear it, allowing the user to re-enter the correct information.

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

class OTPPinWidget extends StatefulWidget {
  final int length;
  final bool isPassword;
  final Function(String)? onComplete;
  final double height;
  final double width;
  final double spaceBetween;
  final double borderRadius;
  final double borderWidth;
  final Color borderColor;
  final Color fillColor;
  final MainAxisAlignment mainAxisAlignment;
  final bool isError;

  const OTPPinWidget({
    super.key,
    required this.length,
    required this.isPassword,
    this.onComplete,
    this.height = 54,
    this.width = 54,
    this.spaceBetween = 16,
    this.borderRadius = 8,
    this.borderWidth = 1,
    this.borderColor = Colors.black,
    this.fillColor = Colors.transparent,
    this.mainAxisAlignment = MainAxisAlignment.spaceBetween,
    this.isError = false,
  });

  @override
  _OTPPinWidgetState createState() => _OTPPinWidgetState();
}

class _OTPPinWidgetState extends State<OTPPinWidget> {
  late List<TextEditingController> _controllers;
  late List<FocusNode> _focusNodes;
  final FocusNode _keyboardFocusNode = FocusNode();

  @override
  void initState() {
    super.initState();
    _controllers = List.generate(widget.length, (_) => TextEditingController());
    _focusNodes = List.generate(widget.length, (_) => FocusNode());
  }

  @override
  void dispose() {
    for (var controller in _controllers) {
      controller.dispose();
    }
    for (var focusNode in _focusNodes) {
      focusNode.dispose();
    }
    _keyboardFocusNode.dispose();
    super.dispose();
  }

  void clearTextFields() {
    for (var controller in _controllers) {
      controller.clear();
    }
  }

  void handleBackspace() {
    for (int i = widget.length - 1; i >= 0; i--) {
      if (_focusNodes[i].hasFocus) {
        if (_controllers[i].text.isEmpty && i > 0) {
          _focusNodes[i - 1].requestFocus();
          _controllers[i - 1].clear();
          break;
        }
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    if (widget.isError) {
      clearTextFields();
    }

    return Focus(
      focusNode: _keyboardFocusNode,
      onKeyEvent: (FocusNode node, KeyEvent event) {
        if (event is KeyDownEvent) {
          if (event.logicalKey == LogicalKeyboardKey.backspace ||
              event.logicalKey == LogicalKeyboardKey.clear) {
            print('Backspace pressed');
            handleBackspace();
            return KeyEventResult.handled;
          }
        }
        return KeyEventResult.ignored;
      },
      child: Row(
        mainAxisAlignment: widget.mainAxisAlignment,
        children: List.generate(widget.length, (index) {
          return Container(
            decoration: BoxDecoration(
              border: Border.all(
                  width: widget.borderWidth, color: widget.borderColor),
              borderRadius: BorderRadius.circular(widget.borderRadius),
            ),
            child: SizedBox(
              width: widget.width,
              height: widget.height,
              child: TextFormField(
                controller: _controllers[index],
                focusNode: _focusNodes[index],
                textAlign: TextAlign.center,
                keyboardType: TextInputType.number,
                obscureText: widget.isPassword,
                obscuringCharacter: '●',
                maxLength: 1,
                textInputAction: index == widget.length - 1
                    ? TextInputAction.done
                    : TextInputAction.next,
                inputFormatters: [
                  FilteringTextInputFormatter.allow(RegExp(r'[0-9]'))
                ],
                onChanged: (value) {
                  if (value.isNotEmpty) {
                    if (index < widget.length - 1) {
                      FocusScope.of(context).nextFocus();
                    } else {
                      FocusScope.of(context).unfocus();
                    }
                    final otp = _controllers
                        .map((controller) => controller.text)
                        .join();
                    if (widget.onComplete != null) {
                      widget.onComplete!(otp);
                    }
                  }
                },
                onTap: () {
                  _controllers[index].selection = TextSelection.fromPosition(
                    TextPosition(offset: _controllers[index].text.length),
                  );
                },
                decoration: InputDecoration(
                  contentPadding: EdgeInsetsDirectional.only(
                      start: 4, top: widget.isPassword ? 36 : 24),
                  counter: const SizedBox.shrink(),
                  enabledBorder: OutlineInputBorder(
                    borderRadius: BorderRadius.circular(widget.borderRadius),
                    borderSide:
                        const BorderSide(width: 0, color: Colors.transparent),
                  ),
                  focusedBorder: OutlineInputBorder(
                    borderRadius: BorderRadius.circular(widget.borderRadius),
                    borderSide:
                        const BorderSide(width: 0, color: Colors.transparent),
                  ),
                  fillColor: widget.fillColor,
                  filled: true,
                  isDense: true,
                  counterText: '',
                ),
                style: TextStyle(
                  color: const Color(0xFF221F1F),
                  fontSize: widget.isPassword ? 12 : 18,
                  fontWeight: FontWeight.w700,
                ),
              ),
            ),
          );
        }),
      ),
    );
  }
}