Using Bluetooth in Mobile Apps

What It Is & How It Works

What You Can Build With It

Permissions & Setup

iOS prompts for Bluetooth on first use. Android 12+ uses the new "Nearby devices" runtime prompt for SCAN/CONNECT/ADVERTISE.

Code Examples

import { BleManager } from 'react-native-ble-plx';

const manager = new BleManager();

export async function findHeartRateMonitor() {
  return new Promise<string | null>((resolve) => {
    const sub = manager.startDeviceScan(['180D'], null, (err, device) => {
      if (err || !device) return;
      manager.stopDeviceScan();
      sub?.remove?.();
      device.connect()
        .then(d => d.discoverAllServicesAndCharacteristics())
        .then(d => d.monitorCharacteristicForService(
          '180D',
          '2A37',
          (_, char) => {
            const bpm = char?.value ? parseHeartRate(char.value) : null;
            console.log('HR:', bpm);
          }
        ));
      resolve(device.id);
    });
    setTimeout(() => { manager.stopDeviceScan(); resolve(null); }, 10_000);
  });
}

function parseHeartRate(base64: string): number {
  const bytes = Buffer.from(base64, 'base64');
  return bytes[1];
}

Tip: With Newly, you describe the feature you want and the AI agent wires up the sensor, permissions, and UI for you. Try it free.

Best Practices

• Scan with service UUIDs

  Filtering by service UUID is faster, drains less battery, and bypasses some Android scan-throttling.

• Stop scanning as soon as you find what you need

  Background scanning is one of the fastest ways to drain a phone's battery.

• Honour MTU negotiation

  Default MTU is tiny (23 bytes); negotiate up to 247 for big payloads.

• Use State Restoration on iOS

  Lets your app reconnect to known peripherals when the OS launches you in the background.

Common Pitfalls

When To Use It (And When Not To)

Frequently Asked Questions

Build with the Bluetooth on Newly

Want a deeper dive on the underlying APIs? See Expo Sensors, Apple Core Motion and Android sensor framework.