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react-nativeexpobluetooth-lowenergyreact-native-ble-plx

Cannot Create BLE Manager

Hello I am new at React Native and in my application I am trying to scan ble devices and list their names on screen. In code sources people most commonly create a Bluetooth Low Energy Manager as const manager = new BleManager(); but when I tried this code (and of course other ways too) it gives error like

TypeError: null is not an object (evaluating '_BleModule.BleModule.createClient')

This error is located at:
    in HelloWorldApp (created by ExpoRoot)
    in ExpoRoot
    in RCTView (created by View)
    in View (created by AppContainer)
    in RCTView (created by View)
    in View (created by AppContainer)
    in AppContainer
at node_modules\react-native\Libraries\LogBox\LogBox.js:149:8 in registerError
at node_modules\react-native\Libraries\LogBox\LogBox.js:60:8 in errorImpl
at node_modules\react-native\Libraries\LogBox\LogBox.js:34:4 in console.error
at node_modules\expo\build\environment\react-native-logs.fx.js:27:4 in error
at node_modules\react-native\Libraries\Core\ExceptionsManager.js:104:6 in reportException
at node_modules\react-native\Libraries\Core\ExceptionsManager.js:172:19 in handleException
at node_modules\react-native\Libraries\Core\ReactFiberErrorDialog.js:43:2 in showErrorDialog
at node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:15792:34 in logCapturedError        
at node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:15884:20 in update.callback
at node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:7199:2 in callCallback
at node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:7220:20 in commitUpdateQueue
at node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:16632:25 in commitLifeCycles        
at node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:19216:22 in commitLayoutEffects     
at node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:93:4 in invokeGuardedCallbackProd
at node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:318:2 in invokeGuardedCallback      
at node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:18952:29 in commitRootImpl
at node_modules\scheduler\cjs\scheduler.development.js:468:23 in unstable_runWithPriority
at node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:18791:17 in commitRoot
at node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:18192:12 in performSyncWorkOnRoot   
at node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:5911:33 in runWithPriority$argument_1
at node_modules\scheduler\cjs\scheduler.development.js:468:23 in unstable_runWithPriority
at node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:5906:23 in flushSyncCallbackQueueImpl
at node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:5893:28 in flushSyncCallbackQueue
at node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:17745:30 in scheduleUpdateOnFiber   
at node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:21484:23 in updateContainer
at node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:22144:17 in render
at node_modules\react-native\Libraries\ReactNative\renderApplication.js:58:4 in renderApplication
at node_modules\react-native\Libraries\ReactNative\AppRegistry.js:117:25 in runnables.appKey.run
at node_modules\react-native\Libraries\ReactNative\AppRegistry.js:202:4 in runApplication
at node_modules\react-native\Libraries\BatchedBridge\MessageQueue.js:414:4 in __callFunction
at node_modules\react-native\Libraries\BatchedBridge\MessageQueue.js:113:6 in __guard$argument_0
at node_modules\react-native\Libraries\BatchedBridge\MessageQueue.js:365:10 in __guard
at node_modules\react-native\Libraries\BatchedBridge\MessageQueue.js:112:4 in callFunctionReturnFlushedQueue

Here is my code that I tried to create a manager:

import { StatusBar } from 'expo-status-bar';
import React, { Component } from 'react';
import { StyleSheet, Text, View } from 'react-native';
import { BleManager } from 'react-native-ble-plx';

const HelloWorldApp = () => {
  const manager = new BleManager();

I cannot solve where is my mistake. Please anyone can help me to solve this issue?

Note: I also installed ble-plx package using npm install --save react-native-ble-plx command.

Note2:I created my project using expo.

Solution

  • You might need to ask the user for permission before using Bluetooth. Add these to your android-manifest.xml :

    <uses-feature android:name="android.hardware.bluetooth" android:required="true"/>
<uses-feature android:name="android.hardware.bluetooth_le" android:required="true"/>