I’m trying to write code so my android app could read/write NFC tags from a screen. I use Kotlin and Jetpack Compose. I have one MainActivity.kt and two screens: HomeScreen.kt and NFCReader.kt. A button on HomeScreen.kt will open NFCReader.kt and a button on NFCReader.kt will start the read/write process.

I have tried using DisposableEffect but for some reason, it keeps triggering the phone’s default NFC scanner.

Below is my code for DisposableEffect. I checked the logcat after every run and I couldn’t find the log so I believe the I might not implement the effect correctly? Please help, TIA.

@Composable
fun NFCReader(
    lifecycleOwner: LifecycleOwner = LocalLifecycleOwner.current
) {
    val nfcAdapter = NfcAdapter.getDefaultAdapter(activity)
    val activity = LocalContext.current.getActivity() as ComponentActivity
    val context = LocalContext.current

    DisposableEffect(lifecycleOwner) {
        val observer = LifecycleEventObserver { _, event ->
            if (event == Lifecycle.Event.ON_RESUME) {
                Log.d("TAG_", "turn on NFC reader here")
                val pendingIntent = PendingIntent.getActivity(
                    activity, 0, Intent(activity, javaClass).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP),
                    PendingIntent.FLAG_MUTABLE
                )
                val intentFilters = arrayOf<IntentFilter>(
                    IntentFilter(NfcAdapter.ACTION_NDEF_DISCOVERED),
                    IntentFilter(NfcAdapter.ACTION_TAG_DISCOVERED),
                    IntentFilter(NfcAdapter.ACTION_TECH_DISCOVERED)
                )
                nfcAdapter.enableForegroundDispatch(activity, pendingIntent, intentFilters, null)
            }
            if (event == Lifecycle.Event.ON_PAUSE) {
                Log.d("TAG_", "turn off NFC reader")
                nfcAdapter.disableForegroundDispatch(activity)
            }
        }
        lifecycleOwner.lifecycle.addObserver(observer)

        val listener = Consumer<Intent> {
            // Do something
            Log.d("TAG_", "inside listener")
        }
        activity.addOnNewIntentListener(listener)
        onDispose {
            activity1.removeOnNewIntentListener(listener)
            lifecycleOwner.lifecycle.removeObserver(observer)
        }
    }
}