Features

• Distance + direction — sub-10 cm distance and azimuth/elevation when the hardware supports it.
• No signalling server — peers find each other over BLE; the plugin handles the UWB token exchange.
• One API, two platforms — same Dart surface for Android (androidx.core.uwb) and iOS (NearbyInteraction).
• Apple FiRa accessories — talk to Qorvo, NXP and other certified tags out of the box.
• End-to-end encrypted — Android↔Android sessions are keyed by an X25519 ECDH handshake over BLE OOB.
• Streams everywhere — discovery, ranging samples, errors, and lifecycle events as Streams you can plug into any state-management solution.

Platform support

isUwbAvailable() returns false on emulators, the iOS simulator, and devices without a UWB chip — always check it before calling discovery.

iOS 26 / U2 chip caveat. Apple disabled supportsDirectionMeasurement for the U2 chip on iOS 26, so iPhone 15 Pro / Pro Max and the iPhone 16 series report null for azimuthDegrees and elevationDegrees. Distance is unaffected.

Cross-OS (iPhone ↔ Android) is experimental in 0.4.0. BLE handshake and Android UWB session activation complete, but androidx.core.uwb rejects the slot duration Apple selects, so stable distance samples are not yet delivered. Same-OS pairs (iOS↔iOS, Android↔Android) are stable. iPhones are auto-discovered on Android and vice-versa — no registerAccessoryProfile boilerplate is needed for cross-OS.

Installation

flutter pub add flutter_uwb

Requires Flutter >=3.22 and Dart >=3.3.

Quick start

Both peers run the same code. Pick a unique localName for each side.

import 'package:flutter_uwb/flutter_uwb.dart';

final uwb = FlutterUwb.instance;

if (!await uwb.isUwbAvailable()) return;

await uwb.startDiscovery('phone-A');

uwb.deviceFound.listen((device) async {
  await uwb.pairWith(device.id);     // exchanges UWB tokens
  await uwb.startRanging(device.id); // begin streaming samples
});

uwb.rangingSamples.listen((s) {
  print('${s.distanceMeters.toStringAsFixed(2)} m  '
        '${s.azimuthDegrees?.toStringAsFixed(1)}°');
});

When you're done:

await uwb.stopRanging();
await uwb.stopDiscovery();

Both peers must call pairWith before either calls startRanging. Trigger this from your own UI (a button, a QR scan, a server event — whatever fits).

A complete runnable demo lives in example/.

API

RangingSample exposes distanceMeters, azimuthDegrees, elevationDegrees, elapsedRealtimeNanos and the originating deviceId. All mutating methods throw UwbException on failure.

startRanging accepts an optional RangingOptions(cameraAssist, extendedDistance) for iOS opt-ins. Use getDeviceCapabilities() to gate the toggles in your UI.

For accessory mode (Qorvo, NXP, third-party FiRa tags), use registerAccessoryProfile(serviceUuid, rxUuid, txUuid, vendorTag). iPhones running flutter_uwb are auto-discovered on Android without this step.

Full API docs: pub.dev/documentation/flutter_uwb/latest/

Permissions

import android.Manifest
import android.os.Build
import androidx.core.app.ActivityCompat

private val perms: Array<String> = buildList {
  if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
    add(Manifest.permission.BLUETOOTH_SCAN)
    add(Manifest.permission.BLUETOOTH_ADVERTISE)
    add(Manifest.permission.BLUETOOTH_CONNECT)
  } else {
    add(Manifest.permission.ACCESS_FINE_LOCATION)
  }
  if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
    add(Manifest.permission.UWB_RANGING)
  }
}.toTypedArray()

ActivityCompat.requestPermissions(this, perms, /*requestCode*/ 1)

<key>NSNearbyInteractionUsageDescription</key>
<string>Used to measure precise distance to nearby devices over UWB.</string>

<key>NSBluetoothAlwaysUsageDescription</key>
<string>Used to discover nearby devices for UWB ranging.</string>

<!-- Required for iOS↔iOS pairing on iOS 17+ (keeps the AWDL sidechannel alive). -->
<key>NSLocalNetworkUsageDescription</key>
<string>Used to coordinate UWB ranging with nearby iPhones.</string>
<key>NSBonjourServices</key>
<array>
  <string>_flutteruwb-uwb._tcp</string>
  <string>_flutteruwb-uwb._udp</string>
</array>

Example app

A runnable cross-platform demo lives in example/. It wires up discovery, pairing, and a live distance/azimuth readout for both same-OS and cross-OS pairs.

Architecture

For protocol details, token format, BLE/UWB topology, the ECDH-keyed Provisioned STS handshake, and the cross-OS capability-flag routing matrix, see doc/architecture.md.

License

MIT