useNFC

Source: packages/sdk/src/hardware/useNFC.ts

Real NFC: adapter state, plus NDEF tag reading and writing through reader mode. startReader enables NfcAdapter reader mode on the foreground Activity; every tag entering the field arrives as an event carrying its identifier, technologies, capacity, writability and decoded NDEF records. writeText queues a text record for the next tag presented.

Two platform constraints are surfaced rather than hidden: reader mode needs a foreground Activity, so it stops when the app is backgrounded and must be restarted on resume; and a tag is only readable while it is physically in the field. It subscribes to onNfcTag and onNfcError on mount and releases reader mode on unmount.

Signature

function useNFC(): {
 isSupported: boolean;
 isEnabled: boolean;
 observeModeSupported: boolean;
 antennaState: 'ENABLED' | 'DISABLED' | 'UNAVAILABLE';
 isReading: boolean;
 lastScannedTag: ScannedTag | null;
 tagCount: number;
 pendingWrite: string | null;
 lastWriteOk: boolean | null;
 error: string | null;
 source: TelemetrySource;
 startReader: () => Promise<boolean>;
 stopReader: () => Promise<void>;
 writeText: (text: string) => Promise<boolean>;
 clearTag: () => void;
};

Outputs

Field	Type	Description
isSupported	boolean	Whether the device has an NFC radio.
isEnabled	boolean	Whether NFC is switched on in system settings. The reader refuses when it is not.
observeModeSupported	boolean	Whether Android 15 Observe Mode is available on this adapter.
antennaState	'ENABLED' | 'DISABLED' | 'UNAVAILABLE'	Antenna state as the adapter reports it.
isReading	boolean	Whether reader mode is running. It stops when the app leaves the foreground.
lastScannedTag	ScannedTag | null	The last tag read: id (hex UID), payload (best single string: a URI if present, else the first text record), tech, timestamp, techs[], records[] ({ tnf, type, payload, bytes, uri }), maxSize (capacity in bytes), writable, ndefType. null before the first tag.
tagCount	number	How many tags have been read since mount.
pendingWrite	string | null	Text waiting to be written to the next tag presented, or null when nothing is queued.
lastWriteOk	boolean | null	Whether the last queued write succeeded. null when none has been attempted.
error	string | null	Why the last operation failed — refused reader, write failure, or a tag error.
source	TelemetrySource	'hardware' when the native module is present, 'unavailable' otherwise.

Functions

Function	Inputs	Returns	Description
startReader()	none	Promise<boolean> — true when reader mode started; false with a reason in error when the build has no reader, the device has no radio, or NFC is off	Enables NfcAdapter reader mode on the foreground Activity. Tags then arrive as events.
stopReader()	none	Promise<void>	Disables reader mode, clears any pending write and logs how many tags were read.
writeText(text)	text: string — the text record to write	Promise<boolean> — true when the write was queued, not when it completed; the outcome arrives later as lastWriteOk	Queues an NDEF text record for the next tag presented. Requires the reader to be running.
clearTag()	none	void	Clears lastScannedTag and lastWriteOk, for a “scan another” control.