An easy to use NFC library for Android to read Ndef-Tags in the foreground. It's meant to be used by inexperienced and experienced developers alike as it allows full customization.
Checkout the NfcLib for iOS NfcLib-iOS
Gradle: 
repositories { mavenCentral() google() maven { url 'https://jitpack.io' } } dependencies { implementation 'com.github.Maliotis:NFCLib-Android:${latestVersion}' }<uses-permission android:name="android.permission.NFC" />Don't enable NFC in the foreground in the onCreate method instead enable it in onResume or during i.e press of a button
private lateinit var readNFC: ReadNFC override fun onResume() { super.onResume() //... readNFC = NFCFactory.create<ReadNFC>(this) readNFC.enableNFCInForeground() } override fun onNewIntent(intent: Intent) { super.onNewIntent(intent) //... if (intent.action == NfcAdapter.ACTION_TECH_DISCOVERED) { readNFC.connect(intent) val payload = readNFC.payload() payload.forEach { Log.d("TAG", "onNewIntent: $it") } } }private lateinit var writeNFC: WriteNFC override fun onResume() { super.onResume() //... writeNFC = NFCFactory.create<WriteNFC>(this) writeNFC.enableNFCInForeground() } override fun onNewIntent(intent: Intent) { super.onNewIntent(intent) //... if (intent.action == NfcAdapter.ACTION_TECH_DISCOVERED) { writeNFC.connect(intent) val succeeded = writeNFC.write("Hello from NfcLib :)") Log.d("TAG", "onNewIntent: succeeded = $succeeded") // when in write mode close the connection writeNFC.close() } }Don't attempt to read directly after a write operation, remove the tag and read in the next tag discovery
private lateinit var readNFC: ReadNFC private lateinit var writeNFC: WriteNFC private var flagRead = true override fun onResume() { super.onResume() readNFC = NFCFactory.create<ReadNFC>(this) writeNFC = NFCFactory.create<WriteNFC>(this) // use only one object to enable nfc in foreground writeNFC.enableNFCInForeground() } override fun onNewIntent(intent: Intent) { super.onNewIntent(intent) //... if (intent.action == NfcAdapter.ACTION_TECH_DISCOVERED) { if (flagRead) { // read from tag readNFC.connect(intent) val payload = readNFC.payload() payload.forEach { Log.d("TAG", "onNewIntent: $it") } } else { // write to tag writeNFC.connect(intent) val succeeded = writeNFC.write("Hello from NfcLib :)") Log.d("TAG", "onNewIntent: succeeded = $succeeded") writeNFC.close() } } } The library allows for full customization by overriding the connectInterface in each write and read operations from here on you are in full control of the tags and the connections.
override fun onNewIntent(intent: Intent) { super.onNewIntent(intent) if (intent.action == NfcAdapter.ACTION_TECH_DISCOVERED) { // Determine the action if (writeAction) { // Handle the connection interface i.e implement behavior for NfcA, MIFARE e.t.c writeNFC.connectInterface = object: ConnectInterface { override fun attemptConnect(tag: Tag) { //TODO("Not yet implemented") } } // Handle the Ndef tag connection writeNFC.ndefFunction = { // return the Ndef Tag } writeNFC.connect(intent) writeNFC.nfcTech = NfcTech.NDEF writeNFC.localeLanguage = Locale.ENGLISH // Change the language writeNFC.tnf = NdefRecord.TNF_ABSOLUTE_URI // Change the TNF value writeNFC.utfEncoding = Charsets.UTF_16 // Change the encoding // Type record is used only in TNF_WELL_KNOWN writeNFC.typeRecord = NdefRecord.RTD_URI // Change the type record writeNFC.write("Hello from NFCLib :)") // Check the write(String) implementation for passing byteArray //writeNFC.write(/*ByteArray*/) // Check the write(String) implementation for passing NdefMessage //writeNFC.write(/*NdefMessage*/) // In write transaction DON'T forget to close the connection writeNFC.close() } if (readAction) { // Change the nfc technology readNFC.nfcTech = NfcTech.NDEF // Handle the connection interface i.e implement behavior for NfcA, MIFARE e.t.c readNFC.connectInterface = object: ConnectInterface { override fun attemptConnect(tag: Tag) { //TODO("Not yet implemented") } } // Handle the Ndef tag connection and access to the payload readNFC.ndefFunction = { // the function requires to return the Ndef message } readNFC.connect(intent) val message = readNFC.message() // return the NdefMessage val records = readNFC.records() // return the NdefRecords val payload = readNFC.payload() payload.forEach { Log.d("TAG", "onNewIntent: $it") } } } } The below example has been taken from the library, use it as a guide
writeNFC.connectInterface = object: ConnectInterface { override fun attemptConnect(tag: Tag) { val technologies = tag.techList val tagTechs = listOf(*technologies) val nfcTechName = nfcTech.canonicalName if (tagTechs.contains(nfcTechName) && nfcTech == NfcTech.NDEF) { tagTechnology = ndefFunction(tag) } else if (tagTechs.contains(nfcTechName) && nfcTech == NfcTech.NDEF_FORMATTABLE) { } else if (tagTechs.contains(nfcTechName) && nfcTech == NfcTech.MIFARE_CLASSIC) { // TODO } else if (tagTechs.contains(nfcTechName) && nfcTech == NfcTech.MIFARE_ULTRALIGHT) { // TODO } } } The below example has been taken from the library, use it as a guide
readNFC.connectInterface = object: ConnectInterface { override fun attemptConnect(tag: Tag) { val technologies = tag.techList val tagTechs = listOf(*technologies) val nfcTechName = nfcTech.canonicalName if (tagTechs.contains(nfcTechName) && nfcTech == NDEF) { ndefMessage = ndefFunction(tag) } else if (tagTechs.contains(nfcTechName) && nfcTech == NFCA) { nfcAFunction(tag) } else if (tagTechs.contains(nfcTechName) && nfcTech == NFCB) { // TODO } else if (tagTechs.contains(nfcTechName) && nfcTech == NFCV) { // TODO } else if (tagTechs.contains(nfcTechName) && nfcTech == NFCF) { // TODO } else if (tagTechs.contains(nfcTechName) && nfcTech == MIFARE_CLASSIC) { // TODO } else if (tagTechs.contains(nfcTechName) && nfcTech == MIFARE_ULTRALIGHT) { // TODO } } }The below example has been taken from the library, use it as a guide
readNFC.ndefFunction = { tag -> val ndefTag = Ndef.get(tag) var ndefMessage: NdefMessage? = null ndefTag.let { it.connect() ndefMessage = it.cachedNdefMessage it.close() } if (ndefMessage == null) throw RuntimeException("Couldn't connect to nfc tag\n" + "Ndef Message is null\n" + "Exiting..") ndefMessage!! }The below example has been taken from the library, use it as a guide
writeNFC.ndefFunction = { val tagTechnology = Ndef.get(it) tagTechnology.connect() tagTechnology }For further reading please visit anrdroid developers site Android-NFC
