How to read identifier number nfc card with nfc_manager - flutter

Question

I can´t to read identifier nfc card with nfc_manager package. I think i need decoded the tag identifier number. My code...
'''ValueNotifier<dynamic> result = ValueNotifier(null);'''
void _tagRead() async{
bool isAvailable = await NfcManager.instance.isAvailable();
NfcManager.instance.startSession(onDiscovered: (NfcTag tag) async {
result.value = tag.data;
MifareClassic? nfca = MifareClassic.from(tag);
var read = nfca?.identifier;
}
It´s returning: identifier[xxx, xx, xxx, xx] (four int numbers).

Answer 1

I used the nfc_manager package and I also didn't get the expected result in my project, so I started using the flutter_nfc_kit package. Only with 'tag.id' has access to the identifier.
Below is a snippet of code taken from the example available at https://github.com/nfcim/flutter_nfc_kit
import 'dart:async';
import 'dart:io' show Platform, sleep;
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_nfc_kit/flutter_nfc_kit.dart';
import 'package:logging/logging.dart';
import 'package:ndef/ndef.dart' as ndef;
class Sensors extends StatefulWidget {
#override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<Sensors> with SingleTickerProviderStateMixin {
String _platformVersion = '';
NFCAvailability _availability = NFCAvailability.not_supported;
NFCTag? _tag;
String? _result, _writeResult;
late TabController _tabController;
List<ndef.NDEFRecord>? _records;
#override
void dispose() {
_tabController.dispose();
super.dispose();
}
#override
void initState() {
super.initState();
if (!kIsWeb)
_platformVersion =
'${Platform.operatingSystem} ${Platform.operatingSystemVersion}';
else
_platformVersion = 'Web';
initPlatformState();
_tabController = new TabController(length: 2, vsync: this);
_records = [];
}
// Platform messages are asynchronous, so we initialize in an async method.
Future<void> initPlatformState() async {
NFCAvailability availability;
try {
availability = await FlutterNfcKit.nfcAvailability;
} on PlatformException {
availability = NFCAvailability.not_supported;
}
// If the widget was removed from the tree while the asynchronous platform
// message was in flight, we want to discard the reply rather than calling
// setState to update our non-existent appearance.
if (!mounted) return;
setState(() {
// _platformVersion = platformVersion;
_availability = availability;
});
}
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(
title: const Text('NFC Flutter Kit Example App'),
),
body: Scrollbar(
child: SingleChildScrollView(
child: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
const SizedBox(height: 20),
Text('Running on: $_platformVersion\nNFC: $_availability'),
const SizedBox(height: 10),
ElevatedButton(
onPressed: () async {
try {
NFCTag tag = await FlutterNfcKit.poll();
setState(() {
_tag = tag;
});
await FlutterNfcKit.setIosAlertMessage("Working on it...");
if (tag.standard == "ISO 14443-4 (Type B)") {
String result1 =
await FlutterNfcKit.transceive("00B0950000");
String result2 = await FlutterNfcKit.transceive(
"00A4040009A00000000386980701");
setState(() {
_result = '1: $result1\n2: $result2\n';
});
} else if (tag.type == NFCTagType.iso18092) {
String result1 =
await FlutterNfcKit.transceive("060080080100");
setState(() {
_result = '1: $result1\n';
});
} else if (tag.type == NFCTagType.mifare_ultralight ||
tag.type == NFCTagType.mifare_classic ||
tag.type == NFCTagType.iso15693) {
var ndefRecords = await FlutterNfcKit.readNDEFRecords();
var ndefString = '';
for (int i = 0; i < ndefRecords.length; i++) {
ndefString += '${i + 1}: ${ndefRecords[i]}\n';
}
setState(() {
_result = ndefString;
});
} else if (tag.type == NFCTagType.webusb) {
var r = await FlutterNfcKit.transceive(
"00A4040006D27600012401");
print(r);
}
} catch (e) {
setState(() {
_result = 'error: $e';
});
}
// Pretend that we are working
if (!kIsWeb) sleep(new Duration(seconds: 1));
await FlutterNfcKit.finish(iosAlertMessage: "Finished!");
},
child: Text('Start polling'),
),
const SizedBox(height: 10),
Padding(
padding: const EdgeInsets.symmetric(horizontal: 20),
child: _tag != null
? Text(
'ID: ${_tag!.id}\nStandard: ${_tag!.standard}\nType: ${_tag!.type}\nATQA: ${_tag!.atqa}\nSAK: ${_tag!.sak}\nHistorical Bytes: ${_tag!.historicalBytes}\nProtocol Info: ${_tag!.protocolInfo}\nApplication Data: ${_tag!.applicationData}\nHigher Layer Response: ${_tag!.hiLayerResponse}\nManufacturer: ${_tag!.manufacturer}\nSystem Code: ${_tag!.systemCode}\nDSF ID: ${_tag!.dsfId}\nNDEF Available: ${_tag!.ndefAvailable}\nNDEF Type: ${_tag!.ndefType}\nNDEF Writable: ${_tag!.ndefWritable}\nNDEF Can Make Read Only: ${_tag!.ndefCanMakeReadOnly}\nNDEF Capacity: ${_tag!.ndefCapacity}\n\n Transceive Result:\n$_result')
: const Text('No tag polled yet.')),
])))),
),
);
}
}