mohemm-flutter-app/lib/widgets/nfc/nfc_reader_sheet.dart

import 'dart:async';
import 'dart:io';

import 'package:flutter/material.dart';
import 'package:nfc_manager/nfc_manager.dart';
import 'package:nfc_manager/platform_tags.dart';

void showNfcReader(BuildContext context, {required Function(String? nfcId) onNcfScan}) {
  showModalBottomSheet(
    context: context,
    enableDrag: false,
    isDismissible: false,
    shape: RoundedRectangleBorder(
      borderRadius: BorderRadius.only(topLeft: Radius.circular(12), topRight: Radius.circular(12)),
    ),
    backgroundColor: Colors.white,
    builder: (context) {
      return NfcLayout(
        onNcfScan: onNcfScan,
      );
    },
  );
}

class NfcLayout extends StatefulWidget {
  Function(String? nfcId) onNcfScan;

  NfcLayout({required this.onNcfScan});

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

class _NfcLayoutState extends State<NfcLayout> {
  bool _reading = false;
  Widget? mainWidget;
  String? nfcId;

  @override
  void initState() {
    super.initState();

    NfcManager.instance.startSession(onDiscovered: (NfcTag tag) async {
      var f;
      if (Platform.isAndroid) {
        f = MifareUltralight(tag: tag, identifier: tag.data["nfca"]["identifier"], type: 2, maxTransceiveLength: 252, timeout: 22);
      } else {
        f = MifareUltralight(tag: tag, identifier: tag.data["mifare"]["identifier"], type: 2, maxTransceiveLength: 252, timeout: 22);
      }
      String identifier = f.identifier.map((e) => e.toRadixString(16).padLeft(2, '0')).join('');
      nfcId = identifier;

      setState(() {
        _reading = true;
        mainWidget = doneNfc();
      });

      Future.delayed(const Duration(seconds: 1), () {
        NfcManager.instance.stopSession();
        Navigator.pop(context);
        // if (Platform.isAndroid) {
        //   Navigator.pop(context);
        // } else {
        //   Navigator.pop(context);
        //   Navigator.pop(context);
        // }
        widget.onNcfScan(nfcId);
      });
    }).catchError((err) {
      print(err);
    });
  }

  @override
  Widget build(BuildContext context) {
    (mainWidget == null && !_reading) ? mainWidget = scanNfc() : mainWidget = doneNfc();
    return AnimatedSwitcher(duration: Duration(milliseconds: 500), child: mainWidget);
  }

  Widget scanNfc() {
    return Container(
      key: ValueKey(1),
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: <Widget>[
          SizedBox(
            height: 30,
          ),
          Text(
            "Ready To Scan",
            style: TextStyle(
              fontWeight: FontWeight.bold,
              fontSize: 24,
            ),
          ),
          SizedBox(
            height: 30,
          ),
          Image.asset(
            "assets/icons/nfc/ic_nfc.png",
            height: MediaQuery.of(context).size.width / 3,
          ),
          SizedBox(
            height: 30,
          ),
          Text(
            "Approach an NFC Tag",
            style: TextStyle(
              fontSize: 18,
            ),
          ),
          SizedBox(
            height: 30,
          ),
          ButtonTheme(
            minWidth: MediaQuery.of(context).size.width / 1.2,
            height: 45.0,
            buttonColor: Colors.grey[300],
            shape: RoundedRectangleBorder(
              borderRadius: BorderRadius.circular(6),
            ),
            child: TextButton(
              onPressed: () {
                NfcManager.instance.stopSession();
                Navigator.pop(context);
              },
              // elevation: 0,
              child: Text("CANCEL"),
            ),
          ),
          SizedBox(
            height: 30,
          ),
        ],
      ),
    );
  }

  Widget doneNfc() {
    return Container(
      key: ValueKey(2),
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: <Widget>[
          SizedBox(
            height: 30,
          ),
          Text(
            "Successfully Scanned",
            style: TextStyle(
              fontWeight: FontWeight.bold,
              fontSize: 24,
            ),
          ),
          SizedBox(
            height: 30,
          ),
          Image.asset(
            "assets/icons/nfc/ic_done.png",
            height: MediaQuery.of(context).size.width / 3,
          ),
          SizedBox(
            height: 30,
          ),
          Text(
            "Approach an NFC Tag",
            style: TextStyle(
              fontSize: 18,
            ),
          ),
          SizedBox(
            height: 30,
          ),
          ButtonTheme(
            minWidth: MediaQuery.of(context).size.width / 1.2,
            height: 45.0,
            buttonColor: Colors.grey[300],
            shape: RoundedRectangleBorder(
              borderRadius: BorderRadius.circular(6),
            ),
            child: TextButton(
              // onPressed: () {
              //   _stream?.cancel();
              //   widget.onNcfScan(nfcId);
              //   Navigator.pop(context);
              // },
              onPressed: null,
              // elevation: 0,
              child: Text("DONE"),
            ),
          ),
          SizedBox(
            height: 30,
          ),
        ],
      ),
    );
  }
}