@pija-ab/react-native-ble-manager

react-native-ble-manager

A React Native Bluetooth Low Energy library.

Originally inspired by https://github.com/don/cordova-plugin-ble-central.

Introduction

The library is a simple connection with the OS APIs, the BLE stack should be standard but often has different behaviors based on the device used, the operating system and the BLE chip it connects to. Before opening an issue verify that the problem is really the library.

Requirements

RN 0.60+

RN 0.40-0.59 supported until 6.7.X RN 0.30-0.39 supported until 2.4.3

Supported Platforms

• iOS 8+
• Android (API 19+)

Install

npm i --save react-native-ble-manager

The library support the react native autolink feature.

Android - Update Manifest

// file: android/app/src/main/AndroidManifest.xml
<!-- Add xmlns:tools -->
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    package="YOUR_PACKAGE_NAME">

    <!--
      HACK: this permission should not be needed on android 12+ devices anymore,
      but in fact some manufacturers still need it for BLE to properly work :
      https://stackoverflow.com/a/72370969
    -->
    <uses-permission android:name="android.permission.BLUETOOTH" tools:remove="android:maxSdkVersion" />
    <!--
      should normally only be needed on android < 12 if you want to:
      - activate bluetooth programmatically
      - discover local BLE devices
      see: https://developer.android.com/guide/topics/connectivity/bluetooth/permissions#discover-local-devices.
      Same as above, may still be wrongly needed by some manufacturers on android 12+.
     -->
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" tools:remove="android:maxSdkVersion" />

    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" android:maxSdkVersion="28"/>
    <uses-permission-sdk-23 android:name="android.permission.ACCESS_FINE_LOCATION" android:maxSdkVersion="30"/>

    <!-- Only when targeting Android 12 or higher -->
    <!--
      Please make sure you read the following documentation
      to have a better understanding of the new permissions.
      https://developer.android.com/guide/topics/connectivity/bluetooth/permissions#assert-never-for-location
    -->

    <!-- Needed if your app search for Bluetooth devices. -->
     <!--
      If your app doesn't use Bluetooth scan results to derive physical location information,
      you can strongly assert that your app doesn't derive physical location.
    -->
    <uses-permission android:name="android.permission.BLUETOOTH_SCAN"
                     android:usesPermissionFlags="neverForLocation" />
    <!-- Needed if you want to interact with a BLE device. -->
    <uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
    <!-- Needed if your app makes the current device discoverable to other Bluetooth devices. -->
    <uses-permission android:name="android.permission.BLUETOOTH_ADVERTISE" />
...

If you need communication while the app is not in the foreground you need the "ACCESS_BACKGROUND_LOCATION" permission.

iOS - Update Info.plist

In iOS >= 13 you need to add the NSBluetoothAlwaysUsageDescription string key.

Note

• Remember to use the start method before anything.
• If you have problem with old devices try avoid to connect/read/write to a peripheral during scan.
• Android API >= 23 require the ACCESS_COARSE_LOCATION permission to scan for peripherals. React Native >= 0.33 natively support PermissionsAndroid like in the example.
• Android API >= 29 require the ACCESS_FINE_LOCATION permission to scan for peripherals. React-Native 0.63.X started targeting Android API 29.
• Before write, read or start notification you need to call retrieveServices method
• Because location and bluetooth permissions are runtime permissions, you must request these permissions at runtime along with declaring them in your manifest.

Example

The easiest way to test is simple make your AppRegistry point to our example component, like this:

// in your index.ios.js or index.android.js
import React, { Component } from "react";
import { AppRegistry } from "react-native";
import App from "react-native-ble-manager/example/App"; //<-- simply point to the example js!
/* 
Note: The react-native-ble-manager/example directory is only included when cloning the repo, the above import will not work 
if trying to import react-native-ble-manager/example from node_modules
*/
AppRegistry.registerComponent("MyAwesomeApp", () => App);

Or, use the example directly

Methods

start(options)

Init the module. Returns a Promise object. Don't call this multiple times.

Arguments

• options - JSON

The parameter is optional the configuration keys are:

• showAlert - Boolean - [iOS only] Show or hide the alert if the bluetooth is turned off during initialization
• restoreIdentifierKey - String - [iOS only] Unique key to use for CoreBluetooth state restoration
• queueIdentifierKey - String - [iOS only] Unique key to use for a queue identifier on which CoreBluetooth events will be dispatched
• forceLegacy - Boolean - [Android only] Force to use the LegacyScanManager

Examples

BleManager.start({ showAlert: false }).then(() => {
  // Success code
  console.log("Module initialized");
});

scan(serviceUUIDs, seconds, allowDuplicates, scanningOptions)

Scan for available peripherals. Returns a Promise object.

Arguments

• serviceUUIDs - Array of String - the UUIDs of the services to looking for. On Android the filter works only for 5.0 or newer.
• seconds - Integer - the amount of seconds to scan.
• allowDuplicates - Boolean - [iOS only] allow duplicates in device scanning
• scanningOptions - JSON - [Android only] after Android 5.0, user can control specific ble scan behaviors:
  • numberOfMatches - Number - [Android only] corresponding to setNumOfMatches. Defaults to ScanSettings.MATCH_NUM_MAX_ADVERTISEMENT. /!\ anything other than default may only work when a ScanFilter is active /!\
  • matchMode - Number - [Android only] corresponding to setMatchMode. Defaults to ScanSettings.MATCH_MODE_AGGRESSIVE.
  • callbackType - Number - [Android only] corresponding to setCallbackType. Defaults ScanSettings.CALLBACK_TYPE_ALL_MATCHES. /!\ anything other than default may only work when a ScanFilter is active /!\
  • scanMode - Number - [Android only] corresponding to setScanMode. Defaults to ScanSettings.SCAN_MODE_LOW_POWER.
  • reportDelay - Number - [Android only] corresponding to setReportDelay. Defaults to 0ms.
  • phy - Number - [Android only] corresponding to setPhy
  • legacy - Boolean - [Android only] corresponding to setLegacy
  • exactAdvertisingName - string - [Android only] corresponds to the ScanFilter deviceName

Examples

BleManager.scan([], 5, true).then(() => {
  // Success code
  console.log("Scan started");
});

stopScan()

Stop the scanning. Returns a Promise object.

Examples

BleManager.stopScan().then(() => {
  // Success code
  console.log("Scan stopped");
});

connect(peripheralId, options)

Attempts to connect to a peripheral. In many case if you can't connect you have to scan for the peripheral before. Returns a Promise object.

In iOS, attempts to connect to a peripheral do not time out (please see Apple's doc), so you might need to set a timer explicitly if you don't want this behavior.

Arguments

• peripheralId - String - the id/mac address of the peripheral to connect.

• options - JSON - The parameter is optional the configuration keys are:

  • phy - Number - [Android only] corresponding to the preferred phy channel (Android doc)
  • autoconnect - Boolean - [Android only] whether to directly connect to the remote device (false) or to automatically connect as soon as the remote device becomes available (true) (Android doc)

Examples

BleManager.connect("XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX")
  .then(() => {
    // Success code
    console.log("Connected");
  })
  .catch((error) => {
    // Failure code
    console.log(error);
  });

disconnect(peripheralId, force)

Disconnect from a peripheral. Returns a Promise object.

Arguments

• peripheralId - String - the id/mac address of the peripheral to disconnect.
• force - boolean - [Android only] defaults to true, if true force closes gatt connection and send the BleManagerDisconnectPeripheral event immediately to Javascript, else disconnects the connection and waits for disconnected state to close the gatt connection and then sends the BleManagerDisconnectPeripheral to the Javascript

Examples

BleManager.disconnect("XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX")
  .then(() => {
    // Success code
    console.log("Disconnected");
  })
  .catch((error) => {
    // Failure code
    console.log(error);
  });

enableBluetooth() [Android only]

Create the request to the user to activate the bluetooth. Returns a Promise object.

Examples

BleManager.enableBluetooth()
  .then(() => {
    // Success code
    console.log("The bluetooth is already enabled or the user confirm");
  })
  .catch((error) => {
    // Failure code
    console.log("The user refuse to enable bluetooth");
  });

checkState()

Force the module to check the state of the native BLE manager and trigger a BleManagerDidUpdateState event. Resolves to a promise containing the current BleState.

Examples

BleManager.checkState().then((state) =>
  console.log(`current BLE state = '${state}'.`)
);

startNotification(peripheralId, serviceUUID, characteristicUUID)

Start the notification on the specified characteristic, you need to call retrieveServices method before. Returns a Promise object.

Arguments

• peripheralId - String - the id/mac address of the peripheral.
• serviceUUID - String - the UUID of the service.
• characteristicUUID - String - the UUID of the characteristic.

Examples

BleManager.startNotification(
  "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
  "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
  "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX"
)
  .then(() => {
    // Success code
    console.log("Notification started");
  })
  .catch((error) => {
    // Failure code
    console.log(error);
  });

startNotificationUseBuffer(peripheralId, serviceUUID, characteristicUUID, buffer) [Android only]

Start the notification on the specified characteristic, you need to call retrieveServices method before. The buffer collect messages until the buffer of messages bytes reaches the limit defined with the buffer argument and then emit all the collected data. Helpful to reducing the number or js bridge crossings when a characteristic is sending a lot of messages. Returns a Promise object.

Arguments

• peripheralId - String - the id/mac address of the peripheral.
• serviceUUID - String - the UUID of the service.
• characteristicUUID - String - the UUID of the characteristic.
• buffer - Integer - the capacity of the buffer (bytes) stored before emitting the data for the characteristic.

Examples

BleManager.startNotification(
  "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
  "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
  "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
  1234
)
  .then(() => {
    // Success code
    console.log("Notification started");
  })
  .catch((error) => {
    // Failure code
    console.log(error);
  });

stopNotification(peripheralId, serviceUUID, characteristicUUID)

Stop the notification on the specified characteristic. Returns a Promise object.

Arguments

• peripheralId - String - the id/mac address of the peripheral.
• serviceUUID - String - the UUID of the service.
• characteristicUUID - String - the UUID of the characteristic.

read(peripheralId, serviceUUID, characteristicUUID)

Read the current value of the specified characteristic, you need to call retrieveServices method before. Returns a Promise object that will resolves to an array of plain integers (number[]) representing a ByteArray structure. That array can then be converted to a JS ArrayBuffer for example using Buffer.from() thanks to this buffer module.

Arguments

• peripheralId - String - the id/mac address of the peripheral.
• serviceUUID - String - the UUID of the service.
• characteristicUUID - String - the UUID of the characteristic.

Examples

BleManager.read(
  "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
  "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
  "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX"
)
  .then((readData) => {
    // Success code
    console.log("Read: " + readData);

    // https://github.com/feross/buffer
    // https://nodejs.org/api/buffer.html#static-method-bufferfromarray
    const buffer = Buffer.from(readData);
    const sensorData = buffer.readUInt8(1, true);
  })
  .catch((error) => {
    // Failure code
    console.log(error);
  });

write(peripheralId, serviceUUID, characteristicUUID, data, maxByteSize)

Write with response to the specified characteristic, you need to call retrieveServices method before. Returns a Promise object.

Arguments

• peripheralId - String - the id/mac address of the peripheral.
• serviceUUID - String - the UUID of the service.
• characteristicUUID - String - the UUID of the characteristic.
• data - number[] - the data to write as a plain integer array representing a ByteArray structure.
• maxByteSize - Integer - specify the max byte size before splitting message, defaults to 20 bytes if not specified

Data preparation

To convert your data to a number[], you should probably be manipulating a Buffer or anything representing a JS ArrayBuffer. This will make sure you are converting from valid byte representations of your data first and not with an integer outside the expected range.

You can create a buffer from files, numbers or strings easily (see examples bellow).

// https://github.com/feross/buffer
import { Buffer } from 'buffer';

 * // Creates a Buffer containing the bytes [0x01, 0x02, 0x03].
 * const buffer = Buffer.from([1, 2, 3]);
 *
 * // Creates a Buffer containing the bytes [0x01, 0x01, 0x01, 0x01] – the entries
 * // are all truncated using `(value & 255)` to fit into the range 0–255.
 * const buffer = Buffer.from([257, 257.5, -255, '1']);
 *
 * // Creates a Buffer containing the UTF-8-encoded bytes for the string 'tést':
 * // [0x74, 0xc3, 0xa9, 0x73, 0x74] (in hexadecimal notation)
 * // [116, 195, 169, 115, 116] (in decimal notation)
 * const buffer = Buffer.from('tést');

Feel free to use other packages or google how to convert into byte array if your data has other format.

Examples

BleManager.write(
  "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
  "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
  "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
  // encode & extract raw `number[]`.
  // Each number should be in the 0-255 range as it is converted from a valid byte.
  buffer.toJSON().data
)
  .then(() => {
    // Success code
    console.log("Write: " + data);
  })
  .catch((error) => {
    // Failure code
    console.log(error);
  });

writeWithoutResponse(peripheralId, serviceUUID, characteristicUUID, data, maxByteSize, queueSleepTime)

Write without response to the specified characteristic, you need to call retrieveServices method before. Returns a Promise object.

Arguments

• peripheralId - String - the id/mac address of the peripheral.
• serviceUUID - String - the UUID of the service.
• characteristicUUID - String - the UUID of the characteristic.
• data - number[] - the data to write as a plain integer array representing a ByteArray structure. (see write()).
• maxByteSize - Integer - (Optional) specify the max byte size
• queueSleepTime - Integer - (Optional) specify the wait time before each write if the data is greater than maxByteSize

Data preparation

If your data is not in number[] format check info fom the write() function example above.

Example

BleManager.writeWithoutResponse(
  "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
  "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
  "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
  data
)
  .then(() => {
    // Success code
    console.log("Writed: " + data);
  })
  .catch((error) => {
    // Failure code
    console.log(error);
  });

readRSSI(peripheralId)

Read the current value of the RSSI. Returns a Promise object resolving with the updated RSSI value (number) if it succeeds.

Arguments

• peripheralId - String - the id/mac address of the peripheral.

Examples

BleManager.readRSSI("XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX")
  .then((rssi) => {
    // Success code
    console.log("Current RSSI: " + rssi);
  })
  .catch((error) => {
    // Failure code
    console.log(error);
  });

readDescriptor(peripheralId, serviceId, characteristicId, descriptorId)

Read the current value of the specified descriptor, you need to call retrieveServices method before. Returns a Promise object that will resolves to an array of plain integers (number[]) representing a ByteArray structure. That array can then be converted to a JS ArrayBuffer for example using Buffer.from() thanks to this buffer module.

Arguments

• peripheralId - String - the id/mac address of the peripheral.
• serviceUUID - String - the UUID of the service.
• characteristicUUID - String - the UUID of the characteristic.
• descriptorUUID - String - the UUID of the descriptor.

Examples

BleManager.readDescriptor(
  "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
  "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
  "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
  "XXXX"
)
  .then((readData) => {
    // Success code
    console.log("Read: " + readData);

    // https://github.com/feross/buffer
    // https://nodejs.org/api/buffer.html#static-method-bufferfromarray
    const buffer = Buffer.from(readData);
    const sensorData = buffer.readUInt8(1, true);
  })
  .catch((error) => {
    // Failure code
    console.log(error);
  });

requestConnectionPriority(peripheralId, connectionPriority) [Android only API 21+]

Request a connection parameter update. Returns a Promise object which fulfills with the status of the request.

Arguments

• peripheralId - String - the id/mac address of the peripheral.
• connectionPriority - Integer - the connection priority to be requested, as follows:
  • 0 - balanced priority connection
  • 1 - high priority connection
  • 2 - low power priority connection

Examples

BleManager.requestConnectionPriority("XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX", 1)
  .then((status) => {
    // Success code
    console.log("Requested connection priority");
  })
  .catch((error) => {
    // Failure code
    console.log(error);
  });

requestMTU(peripheralId, mtu) [Android only API 21+]

Request an MTU size used for a given connection. Returns a Promise object.

Arguments

• peripheralId - String - the id/mac address of the peripheral.
• mtu - Integer - the MTU size to be requested in bytes.

Examples

BleManager.requestMTU("XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX", 512)
  .then((mtu) => {
    // Success code
    console.log("MTU size changed to " + mtu + " bytes");
  })
  .catch((error) => {
    // Failure code
    console.log(error);
  });

retrieveServices(peripheralId[, serviceUUIDs])

Retrieve the peripheral's services and characteristics. Returns a Promise object.

Arguments

• peripheralId - String - the id/mac address of the peripheral.
• serviceUUIDs - String[] - [iOS only] only retrieve these services.

Examples

BleManager.retrieveServices("XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX").then(
  (peripheralInfo) => {
    // Success code
    console.log("Peripheral info:", peripheralInfo);
  }
);

refreshCache(peripheralId) [Android only]

refreshes the peripheral's services and characteristics cache Returns a Promise object.

Arguments

• peripheralId - String - the id/mac address of the peripheral.

Examples

BleManager.refreshCache("XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX")
  .then((peripheralInfo) => {
    // Success code
    console.log("cache refreshed!");
  })
  .catch((error) => {
    console.error(error);
  });

getConnectedPeripherals(serviceUUIDs)

Return the connected peripherals. Returns a Promise object.

Arguments

• serviceUUIDs - Array of String - the UUIDs of the services to looking for.

Examples

BleManager.getConnectedPeripherals([]).then((peripheralsArray) => {
  // Success code
  console.log("Connected peripherals: " + peripheralsArray.length);
});

createBond(peripheralId,peripheralPin) [Android only]

Start the bonding (pairing) process with the remote device. If you pass peripheralPin(optional), bonding will be auto(without manual entering pin) Returns a Promise object that will resolves if the bond is successfully created, otherwise it will be rejected with the appropriate error message.

Examples

BleManager.createBond(peripheralId)
  .then(() => {
    console.log("createBond success or there is already an existing one");
  })
  .catch(() => {
    console.log("fail to bond");
  });

removeBond(peripheralId) [Android only]

Remove a paired device. Returns a Promise object.

Examples

BleManager.removeBond(peripheralId)
  .then(() => {
    console.log("removeBond success");
  })
  .catch(() => {
    console.log("fail to remove the bond");
  });

getBondedPeripherals() [Android only]

Return the bonded peripherals. Returns a Promise object.

Examples

BleManager.getBondedPeripherals([]).then((bondedPeripheralsArray) => {
  // Each peripheral in returned array will have id and name properties
  console.log("Bonded peripherals: " + bondedPeripheralsArray.length);
});

getDiscoveredPeripherals()

Return the discovered peripherals after a scan. Returns a Promise object.

Examples

BleManager.getDiscoveredPeripherals([]).then((peripheralsArray) => {
  // Success code
  console.log("Discovered peripherals: " + peripheralsArray.length);
});

removePeripheral(peripheralId) [Android only]

Removes a disconnected peripheral from the cached list. It is useful if the device is turned off, because it will be re-discovered upon turning on again. Returns a Promise object.

Arguments

• peripheralId - String - the id/mac address of the peripheral.

isPeripheralConnected(peripheralId, serviceUUIDs)

Check whether a specific peripheral is connected and return true or false. Returns a Promise object.

Examples

BleManager.isPeripheralConnected(
  "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
  []
).then((isConnected) => {
  if (isConnected) {
    console.log("Peripheral is connected!");
  } else {
    console.log("Peripheral is NOT connected!");
  }
});

setName(name) [Android only]

Create the request to set the name of the bluetooth adapter. (https://developer.android.com/reference/android/bluetooth/BluetoothAdapter#setName(java.lang.String)) Returns a Promise object.

Examples

BleManager.setName("INNOVEIT_CENTRAL")
  .then(() => {
    // Success code
    console.log("Name set successfully");
  })
  .catch((error) => {
    // Failure code
    console.log("Name could not be set");
  });

getMaximumWriteValueLengthForWithoutResponse(peripheralId) [iOS only]

Return the maximum value length for WriteWithoutResponse. Returns a Promise object.

Examples

BleManager.getMaximumWriteValueLengthForWithoutResponse("XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX").then((maxValue) => {
  console.log("Maximum length for WriteWithoutResponse: " + maxValue);
});

getMaximumWriteValueLengthForWitResponse(peripheralId) [iOS only]

Return the maximum value length for WriteWithResponse. Returns a Promise object.

Examples

BleManager.getMaximumWriteValueLengthForWitResponse("XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX").then((maxValue) => {
  console.log("Maximum length for WriteWithResponse: " + maxValue);
});

Events

BleManagerStopScan

The scanning for peripherals is ended.

Arguments

• status - Number - [iOS] the reason for stopping the scan. Error code 10 is used for timeouts, 0 covers everything else. [Android] the reason for stopping the scan (https://developer.android.com/reference/android/bluetooth/le/ScanCallback#constants_1). Error code 10 is used for timeouts

Examples

bleManagerEmitter.addListener("BleManagerStopScan", (args) => {
  // Scanning is stopped
});

BleManagerDidUpdateState

The BLE change state.

Arguments

• state - String - the new BLE state. can be one of unknown (iOS only), resetting (iOS only), unsupported, unauthorized (iOS only), on, off, turning_on (android only), turning_off (android only).

Examples

bleManagerEmitter.addListener("BleManagerDidUpdateState", (args) => {
  // The new state: args.state
});

BleManagerDiscoverPeripheral

The scanning find a new peripheral.

Arguments

• id - String - the id of the peripheral
• name - String - the name of the peripheral
• rssi - Number - the RSSI value
• advertising - JSON - the advertising payload, here are some examples:
  • isConnectable - Boolean
  • serviceUUIDs - Array of String
  • manufacturerData - JSON - contains the raw bytes and data (Base64 encoded string)
  • serviceData - JSON - contains the raw bytes and data (Base64 encoded string)
  • txPowerLevel - Int

Examples

bleManagerEmitter.addListener("BleManagerDiscoverPeripheral", (args) => {
  // The id: args.id
  // The name: args.name
});

BleManagerDidUpdateValueForCharacteristic

A characteristic notify a new value.

Arguments

• value — Array — the read value
• peripheral — String — the id of the peripheral
• characteristic — String — the UUID of the characteristic
• service — String — the UUID of the characteristic

Event will only be emitted after successful startNotification.

Example

import { bytesToString } from "convert-string";
import { NativeModules, NativeEventEmitter } from "react-native";

const BleManagerModule = NativeModules.BleManager;
const bleManagerEmitter = new NativeEventEmitter(BleManagerModule);

async function connectAndPrepare(peripheral, service, characteristic) {
  // Connect to device
  await BleManager.connect(peripheral);
  // Before startNotification you need to call retrieveServices
  await BleManager.retrieveServices(peripheral);
  // To enable BleManagerDidUpdateValueForCharacteristic listener
  await BleManager.startNotification(peripheral, service, characteristic);
  // Add event listener
  bleManagerEmitter.addListener(
    "BleManagerDidUpdateValueForCharacteristic",
    ({ value, peripheral, characteristic, service }) => {
      // Convert bytes array to string
      const data = bytesToString(value);
      console.log(`Received ${data} for characteristic ${characteristic}`);
    }
  );
  // Actions triggereng BleManagerDidUpdateValueForCharacteristic event
}

BleManagerConnectPeripheral

A peripheral was connected.

Arguments

• peripheral - String - the id of the peripheral
• status - Number - [Android only] connect reasons

BleManagerDisconnectPeripheral

A peripheral was disconnected.

Arguments

• peripheral - String - the id of the peripheral
• status - Number - [Android only] disconnect reasons
• domain - String - [iOS only] disconnect error domain
• code - Number - [iOS only] disconnect error code (https://developer.apple.com/documentation/corebluetooth/cberror/code)

BleManagerPeripheralDidBond

A bond with a peripheral was established

Arguments

Object with information about the device

BleManagerCentralManagerWillRestoreState [iOS only]

This is fired when centralManager:WillRestoreState: is called (app relaunched in the background to handle a bluetooth event).

Arguments

• peripherals - Array - an array of previously connected peripherals.

For more on performing long-term bluetooth actions in the background:

iOS Bluetooth State Preservation and Restoration

iOS Relaunch Conditions

BleManagerDidUpdateNotificationStateFor [iOS only]

The peripheral received a request to start or stop providing notifications for a specified characteristic's value.

Arguments

• peripheral - String - the id of the peripheral
• characteristic - String - the UUID of the characteristic
• isNotifying - Boolean - Is the characteristic notifying or not
• domain - String - [iOS only] error domain
• code - Number - [iOS only] error code

Library development

• the library is written in typescript and needs to be built before being used for publication or local development, using the provided npm scripts in package.json.
• the local example project is configured to work with the locally built version of the library. To be able to run it, you need to build at least once the library so that its outputs listed as entrypoint in package.json (in the dist folder) are properly generated for consumption by the example project:

from the root folder:

npm install
npm run build

if you are modifying the typescript files of the library (in src/) on the fly, you can run npm run watch instead. If you are modifying files from the native counterparts, you'll need to rebuild the whole app for your target environnement (npm run android/ios).