Mobile Platform as a Service:Bluetooth API list

my.openBluetoothAdapter

Initializes the miniapp Bluetooth module. The initialization is effective from the time my.openBluetoothAdapter is called until my.closeBluetoothAdapter is called or the miniapp is destroyed. During this period, you can call other miniapp Bluetooth APIs and receive on event callbacks related to the Bluetooth module.

Input parameters

Success return value

Error code descriptions

Code example

<!-- .axml-->
<view class="page">
  <view class="page-description">Bluetooth API</view>
  <view class="page-section">
    <view class="page-section-title">Local Bluetooth adapter state</view>
    <view class="page-section-demo">
       <button type="primary" onTap="openBluetoothAdapter">Initialize Bluetooth</button>
       <button type="primary" onTap="closeBluetoothAdapter">Close local Bluetooth</button>
       <button type="primary" onTap="getBluetoothAdapterState">Get Bluetooth state</button>
    </view>

    <view class="page-section-title">Scan for Bluetooth devices</view>
    <view class="page-section-demo">
       <button type="primary" onTap="startBluetoothDevicesDiscovery">Start search</button>
       <button type="primary" onTap="getBluetoothDevices">All discovered devices</button>
       <button type="primary" onTap="getConnectedBluetoothDevices">All connected devices</button>
       <button type="primary" onTap="stopBluetoothDevicesDiscovery">Stop search</button>
    </view>

    <view class="page-section-title">Connect to a device</view>
    <view class="page-section-demo">
       <input class="input" onInput="bindKeyInput" type="{{text}}" placeholder="Enter the deviceId of the device to connect to"></input>
       <button type="primary" onTap="connectBLEDevice">Connect to device</button>
       <button type="primary" onTap="getBLEDeviceServices">Get device services</button>
       <button type="primary" onTap="getBLEDeviceCharacteristics">Get read/write characteristics</button>
       <button type="primary" onTap="disconnectBLEDevice">Disconnect from device</button>
    </view>

     <view class="page-section-title">Read and write data</view>
     <view class="page-section-demo">
       <button type="primary" onTap="notifyBLECharacteristicValueChange">Listen for characteristic value changes</button>
       <button type="primary" onTap="readBLECharacteristicValue">Read data</button>
       <button type="primary" onTap="writeBLECharacteristicValue">Write data</button>
       <button type="primary" onTap="offBLECharacteristicValueChange">Cancel characteristic value listener</button>
    </view>

     <view class="page-section-title">Other events</view>
     <view class="page-section-demo">
       <button type="primary" onTap="bluetoothAdapterStateChange">Local Bluetooth state change</button>
       <button type="primary" onTap="offBluetoothAdapterStateChange">Cancel local Bluetooth state listener</button>
       <button type="primary" onTap="BLEConnectionStateChanged">Bluetooth connection state change</button>
       <button type="primary" onTap="offBLEConnectionStateChanged">Cancel Bluetooth connection state listener</button>

    </view>
  </view>
</view>

// .js
Page({
  data: {
    devid: '0D9C82AD-1CC0-414D-9526-119E08D28124',
    serid: 'FEE7',
    notifyId: '36F6',
    writeId: '36F5',
    charid: '',
    alldev: [{ deviceId: '' }],
  },
  // Get the local Bluetooth adapter state
  openBluetoothAdapter() {
    my.openBluetoothAdapter({
      success: res => {
        if (!res.isSupportBLE) {
          my.alert({ content: 'Sorry, Bluetooth is not available on your phone.' });
          return;
        }
        my.alert({ content: 'Initialization successful!' });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },
  closeBluetoothAdapter() {
    my.closeBluetoothAdapter({
      success: () => {
        my.alert({ content: 'Bluetooth closed successfully!' });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },
  getBluetoothAdapterState() {
    my.getBluetoothAdapterState({
      success: res => {
        if (!res.available) {
          my.alert({ content: 'Sorry, Bluetooth is not available on your phone.' });
          return;
        }
        my.alert({ content: JSON.stringify(res) });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },
  // Scan for Bluetooth devices
  startBluetoothDevicesDiscovery() {
    my.startBluetoothDevicesDiscovery({
      allowDuplicatesKey: false,
      success: () => {
        my.onBluetoothDeviceFound({
          success: res => {
            // my.alert({content:'Listening for new devices'+JSON.stringify(res)});
            var deviceArray = res.devices;
            for (var i = deviceArray.length - 1; i >= 0; i--) {
              var deviceObj = deviceArray[i];
              // Match the target device by device name or broadcast data, then record the deviceID for later use
              if (deviceObj.name == this.data.name) {
                my.alert({ content: 'Target device found' });
                my.offBluetoothDeviceFound();
                this.setData({
                  deviceId: deviceObj.deviceId,
                });
                break;
              }
            }
          },
          fail: error => {
            my.alert({ content: 'Failed to listen for new devices' + JSON.stringify(error) });
          },
        });
      },
      fail: error => {
        my.alert({ content: 'Failed to start scan' + JSON.stringify(error) });
      },
    });
  },
  // Stop scanning
  stopBluetoothDevicesDiscovery() {
    my.stopBluetoothDevicesDiscovery({
      success: res => {
        my.offBluetoothDeviceFound();
        my.alert({ content: 'Operation successful!' });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },
  // Get connected devices
  getConnectedBluetoothDevices() {
    my.getConnectedBluetoothDevices({
      success: res => {
        if (res.devices.length === 0) {
          my.alert({ content: 'No connected devices!' });
          return;
        }
        my.alert({ content: JSON.stringify(res) });
        devid = res.devices[0].deviceId;
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },
  // Get all discovered devices
  getBluetoothDevices() {
    my.getBluetoothDevices({
      success: res => {
        my.alert({ content: JSON.stringify(res) });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },
  bindKeyInput(e) {
    this.setData({
      devid: e.detail.value,
    });
  },
  // Connect to a device
  connectBLEDevice() {
    my.connectBLEDevice({
      deviceId: this.data.devid,
      success: res => {
        my.alert({ content: 'Connection successful' });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },
  // Disconnect
  disconnectBLEDevice() {
    my.disconnectBLEDevice({
      deviceId: this.data.devid,
      success: () => {
        my.alert({ content: 'Disconnection successful!' });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },
  // Get the services of a connected device. This must be done while connected.
  getBLEDeviceServices() {
    my.getConnectedBluetoothDevices({
      success: res => {
        if (res.devices.length === 0) {
          my.alert({ content: 'No connected devices' });
          return;
        }
        my.getBLEDeviceServices({
          deviceId: this.data.devid,
          success: res => {
            my.alert({ content: JSON.stringify(res) });
            this.setData({
              serid: res.services[0].serviceId,
            });
          },
          fail: error => {
            my.alert({ content: JSON.stringify(error) });
          },
        });
      },
    });
  },
  // Get the charid of a connected device. This must be done while connected. (This filters for read and write characteristics.)
  getBLEDeviceCharacteristics() {
    my.getConnectedBluetoothDevices({
      success: res => {
        if (res.devices.length === 0) {
          my.alert({ content: 'No connected devices' });
          return;
        }
        this.setData({
          devid: res.devices[0].deviceId,
        });
        my.getBLEDeviceCharacteristics({
          deviceId: this.data.devid,
          serviceId: this.data.serid,
          success: res => {
            my.alert({ content: JSON.stringify(res) });
            // See the document for characteristic object properties. Match and record the read/write characteristics for later use.
            this.setData({
              charid: res.characteristics[0].characteristicId,
            });
          },
          fail: error => {
            my.alert({ content: JSON.stringify(error) });
          },
        });
      },
    });
  },
  // Read and write data
  readBLECharacteristicValue() {
    my.getConnectedBluetoothDevices({
      success: res => {
        if (res.devices.length === 0) {
          my.alert({ content: 'No connected devices' });
          return;
        }
        this.setData({
          devid: res.devices[0].deviceId,
        });
        my.readBLECharacteristicValue({
          deviceId: this.data.devid,
          serviceId: this.data.serid,
          characteristicId: this.data.notifyId,
          // 1. Android read service
          // serviceId:'0000180d-0000-1000-8000-00805f9b34fb',
          // characteristicId:'00002a38-0000-1000-8000-00805f9b34fb',
          success: res => {
            my.alert({ content: JSON.stringify(res) });
          },
          fail: error => {
            my.alert({ content: 'Read failed' + JSON.stringify(error) });
          },
        });
      },
    });
  },
  writeBLECharacteristicValue() {
    my.getConnectedBluetoothDevices({
      success: res => {
        if (res.devices.length === 0) {
          my.alert({ content: 'No connected devices' });
          return;
        }
        this.setData({
          devid: res.devices[0].deviceId,
        });
        my.writeBLECharacteristicValue({
          deviceId: this.data.devid,
          serviceId: this.data.serid,
          characteristicId: this.data.charid,
          // Android write service
          //serviceId:'0000180d-0000-1000-8000-00805f9b34fb',
          //characteristicId:'00002a39-0000-1000-8000-00805f9b34fb',
          value: 'ABCD',
          success: res => {
            my.alert({ content: 'Data written successfully!' });
          },
          fail: error => {
            my.alert({ content: JSON.stringify(error) });
          },
        });
      },
    });
  },
  notifyBLECharacteristicValueChange() {
    my.getConnectedBluetoothDevices({
      success: res => {
        if (res.devices.length === 0) {
          my.alert({ content: 'No connected devices' });
          return;
        }
        this.setData({
          devid: res.devices[0].deviceId,
        });
        my.notifyBLECharacteristicValueChange({
          state: true,
          deviceId: this.data.devid,
          serviceId: this.data.serid,
          characteristicId: this.data.notifyId,
          success: () => {
            // Listen for characteristic value changes
            my.onBLECharacteristicValueChange({
              success: res => {
                //  my.alert({content: 'Characteristic value changed: '+JSON.stringify(res)});
                my.alert({ content: 'Response data received = ' + res.value });
              },
            });
            my.alert({ content: 'Listener enabled successfully' });
          },
          fail: error => {
            my.alert({ content: 'Failed to enable listener' + JSON.stringify(error) });
          },
        });
      },
    });
  },
  offBLECharacteristicValueChange() {
    my.offBLECharacteristicValueChange();
  },
  // Other events
  bluetoothAdapterStateChange() {
    my.onBluetoothAdapterStateChange(this.getBind('onBluetoothAdapterStateChange'));
  },
  onBluetoothAdapterStateChange() {
    if (res.error) {
      my.alert({ content: JSON.stringify(error) });
    } else {
      my.alert({ content: 'Local Bluetooth state changed: ' + JSON.stringify(res) });
    }
  },
  offBluetoothAdapterStateChange() {
    my.offBluetoothAdapterStateChange(this.getBind('onBluetoothAdapterStateChange'));
  },
  getBind(name) {
    if (!this[`bind${name}`]) {
      this[`bind${name}`] = this[name].bind(this);
    }
    return this[`bind${name}`];
  },
  BLEConnectionStateChanged() {
    my.onBLEConnectionStateChanged(this.getBind('onBLEConnectionStateChanged'));
  },
  onBLEConnectionStateChanged(res) {
    if (res.error) {
      my.alert({ content: JSON.stringify(error) });
    } else {
      my.alert({ content: 'Connection state changed: ' + JSON.stringify(res) });
    }
  },
  offBLEConnectionStateChanged() {
    my.offBLEConnectionStateChanged(this.getBind('onBLEConnectionStateChanged'));
  },
  onUnload() {
    this.offBLEConnectionStateChanged();
    this.offBLECharacteristicValueChange();
    this.offBluetoothAdapterStateChange();
    this.closeBluetoothAdapter();
  },
});

Bugs and tips

• Bug: If the user's Bluetooth is turned off or their phone does not support Bluetooth, calling my.openBluetoothAdapter returns an error. For more information about the error codes, see the Bluetooth API Error Code Table. At this point, the miniapp's Bluetooth module is already initialized, and you can use my.onBluetoothAdapterStateChange to listen for changes in the phone's Bluetooth state.

• Tip: If you call other Bluetooth module APIs before calling the my.openBluetoothAdapter API, an error is returned.

  • Error code: 10000

  • Error description: Bluetooth adapter not initialized

  • Solution: Call my.openBluetoothAdapter.

my.closeBluetoothAdapter

Shuts down the local Bluetooth module.

Input parameters

Code example

my.closeBluetoothAdapter({
  success: (res) => {
  },
  fail:(res) => {
  },
  complete: (res)=>{
  }
});

Bugs and tips

• Tip: Calling this method disconnects all established Bluetooth connections and releases system resources.

• Tip: Call this method when the miniapp Bluetooth process ends. It should be paired with my.openBluetoothAdapter.

• Tip: Releasing resources by calling my.closeBluetoothAdapter is an asynchronous operation. Do not use my.closeBluetoothAdapter and my.openBluetoothAdapter in an exception handling flow. This is equivalent to closing and then reopening to re-initialize, which is inefficient and can cause thread synchronization issues.

my.getBluetoothAdapterState

Retrieves the state of the local Bluetooth module.

Input parameters

Success return value

Code example

my.getBluetoothAdapterState({
  success: (res) => {
      console.log(res)
  },
  fail:(res) => {
  },
  complete: (res)=>{
  }
});

my.startBluetoothDevicesDiscovery

Starts searching for nearby Bluetooth peripheral devices. The search results are returned in the my.onBluetoothDeviceFound event.

Input parameters

Code example

my.startBluetoothDevicesDiscovery({
  services: ['fff0'],
  success: (res) => {
      console.log(res)
  },
  fail:(res) => {
  },
  complete: (res)=>{
  }
});

Bugs and tips

• Tip: This operation consumes significant system resources. Call the stop method to stop the search after you find and connect to a device.

my.stopBluetoothDevicesDiscovery

Stops searching for nearby Bluetooth peripheral devices.

Input parameters

Code example

my.stopBluetoothDevicesDiscovery({
  success: (res) => {
    console.log(res)
  },
  fail:(res) => {
  },
  complete: (res)=>{
  }
});

my.getBluetoothDevices

Retrieves all discovered Bluetooth devices, including those already connected to the local device.

Input parameters

Success return value

device object

Code example

my.getBluetoothDevices({
  success: (res) => {
      console.log(res)
  },
  fail:(res) => {
  },
  complete: (res)=>{
  }
});

Bugs and tips

• Tip: The emulator may not be able to retrieve advertisData and RSSI. Use a physical device for debugging.

• Tip: The deviceId obtained from developer tools and Android is the device's MAC address. On iOS, it is the device's UUID. Therefore, do not hard-code the deviceId. You must handle it differently for each platform. On iOS, you can dynamically match the device based on its properties, such as localName, advertisData, or manufacturerData.

my.getConnectedBluetoothDevices

Retrieves all connected devices.

Input parameters

Code example

my.getConnectedBluetoothDevices({
  success: (res) => {
      console.log(res)
  },
  fail:(res) => {
  },
  complete: (res)=>{
  }
});

Bugs and tips

• Tip: If the miniapp has previously discovered a Bluetooth device, you can directly pass the deviceId obtained from the search to connect to the device without searching again.

• Tip: If the specified Bluetooth device is already connected, reconnecting will directly return success.

my.connectBLEDevice

Connects to a Bluetooth Low Energy (BLE) device.

Input parameters

Code example

my.connectBLEDevice({
  // The deviceId here needs to be obtained from the getBluetoothDevices or onBluetoothDeviceFound API.
  deviceId: deviceId,
  success: (res) => {
      console.log(res)
  },
  fail:(res) => {
  },
  complete: (res)=>{
  }
});

Bugs and tips

• Tip: If the miniapp has previously discovered a Bluetooth device, you can directly pass the deviceId obtained from the search to connect to the device without searching again.

• Tip: If the specified Bluetooth device is already connected, reconnecting will directly return success.

• Tip: This feature is supported on iOS clients and Android 5.0 or later clients.

my.disconnectBLEDevice

Disconnects from a BLE device.

Input parameters

Code example

my.disconnectBLEDevice({
  deviceId: deviceId,
  success: (res) => {
      console.log(res)
  },
  fail:(res) => {
  },
  complete: (res)=>{
  }
});

Bugs and tips

• Tip: A Bluetooth connection can be lost at any time. Listen for the my.onBLEConnectionStateChanged callback event to reconnect as needed.

• Tip: If you call a data read/write API for an unconnected or disconnected device, error 10006 is returned. For more information, see the Bluetooth API Error Code Table. We recommend that you reconnect.

• Tip: This feature is supported on iOS clients and Android 5.0 or later clients.

my.writeBLECharacteristicValue

Writes data to a characteristic of a BLE device.

Input parameters

Code example

my.writeBLECharacteristicValue({
  deviceId: deviceId,
  serviceId: serviceId,
  characteristicId: characteristicId,
  value: 'fffe',
  success: (res) => {
      console.log(res)
  },
  fail:(res) => {
  },
  complete: (res)=>{
  }
});

Bugs and tips

• Tip: The device characteristic must support the write operation for this call to succeed. Check the properties attribute of the characteristic.

• Tip: The binary data to be written must be hex-encoded.

• Tip: This feature is supported on iOS clients and Android 5.0 or later clients.

my.readBLECharacteristicValue

Reads data from a characteristic of a BLE device. After the call, the data is returned in the my.onBLECharacteristicValueChange() event.

Input parameters

Success return value

characteristic object

Information about a Bluetooth device characteristic.

Code example

my.readBLECharacteristicValue({
  deviceId: deviceId,
  serviceId: serviceId,
  characteristicId: characteristicId,
  success: (res) => {
      console.log(res)
  },
  fail:(res) => {
  },
  complete: (res)=>{
  }
});

Bugs and tips

• Tip: The device characteristic must support the read operation for this call to succeed. Check the properties attribute of the characteristic.

• Tip: Calling read and write APIs in parallel may cause failures.

• Tip: If a read operation times out with error code 10015, the my.onBLECharacteristicValueChange interface may still return data later, which you must handle accordingly. For more information about error codes and solutions, see the Bluetooth API Error Code Reference.

• Tip: This feature is supported on iOS clients and Android 5.0 or later clients.

my.notifyBLECharacteristicValueChange

Enables the notify feature for characteristic value changes on a BLE device.

Input parameters

Code example

my.notifyBLECharacteristicValueChange({
  deviceId: deviceId,
  serviceId: serviceId,
  characteristicId: characteristicId,
  success: (res) => {
      console.log(res)
  },
  fail:(res) => {
  },
  complete: (res)=>{
  }
});

Bugs and tips

• Tip: The device characteristic must support notify or indicate for this call to succeed. Check the properties attribute of the characteristic.

• Tip: You must enable notify before you can listen for the device's characteristicValueChange event.

• Tip: After a successful subscription, the device must actively update the characteristic's value to trigger my.onBLECharacteristicValueChange.

• Tip: Subscribing is more efficient than reading. We recommend that you use subscriptions instead of the read method.

my.getBLEDeviceServices

You can retrieve all discovered Bluetooth devices, including those that are already connected to the local device.

Input parameters

Success return value

service object

Information about a Bluetooth device service.

Code example

 // Get the services of a connected device. This must be done while connected.
  getBLEDeviceServices() {
    my.getConnectedBluetoothDevices({
      success: res => {
        if (res.devices.length === 0) {
          my.alert({ content: 'No connected devices' });
          return;
        }
        my.getBLEDeviceServices({
          deviceId: this.data.devid,
          success: res => {
            my.alert({ content: JSON.stringify(res) });
            this.setData({
              serid: res.services[0].serviceId,
            });
          },
          fail: error => {
            my.alert({ content: JSON.stringify(error) });
          },
        });
      },
    });
  },

Return value sample

{
    "services": [{
        "isPrimary": true,
        "serviceId": "00001800-0000-1000-8000-00805f9b34fb"
    }, {
        "isPrimary": true,
        "serviceId": "00001801-0000-1000-8000-00805f9b34fb"
    }, {
        "isPrimary": true,
        "serviceId": "d0611e78-bbb4-4591-a5f8-487910ae4366"
    }, {
        "isPrimary": true,
        "serviceId": "9fa480e0-4967-4542-9390-d343dc5d04ae"
    }]
}

Bugs and tips

• Tip: After you establish a connection, execute my.getBLEDeviceServices and my.getBLEDeviceCharacteristics before you interact with the Bluetooth device.

• Tip: This feature is supported on iOS clients and Android 5.0 or later clients.

my.getBLEDeviceCharacteristics

You can retrieve all characteristics of the Bluetooth device.

Input parameters

Success return value

characteristic object

Information about a Bluetooth device characteristic.

properties object

Code example

my.getBLEDeviceCharacteristics({
  deviceId: deviceId,
  serviceId: serviceId,
  success: (res) => {
      console.log(res)
  },
  fail:(res) => {
  },
  complete: (res)=>{
  }
});

Bugs and tips

• Tip: After you establish a connection, execute my.getBLEDeviceServices and my.getBLEDeviceCharacteristics before you interact with the Bluetooth device.

• Tip: This feature is supported on iOS clients and Android 5.0 or later clients.

my.onBluetoothDeviceFound(callback)

This event is triggered when a new Bluetooth device is discovered.

Input parameters

Callback return value

device object

Code example

Page({
  onLoad() {
    this.callback = this.callback.bind(this);
    my.onBluetoothDeviceFound(this.callback);
  },
  onUnload() {
    my.offBluetoothDeviceFound(this.callback);
  },
  callback(res) {
    console.log(res);
  },
})

Bugs and tips

• Tip: The emulator may not be able to retrieve advertisData and RSSI. Use a physical device for debugging.

• Tip: The `deviceId` obtained from developer tools is the device's MAC address on Android, while on iOS, it is the device's UUID. Therefore, do not hard-code the `deviceId`. You should handle it differently for each platform. On iOS, you can dynamically match the device based on its properties, such as localName, advertisData, or manufacturerData.

• Tip: When the my.onBluetoothDeviceFound callback finds a Bluetooth device, the device is added to the array returned by the my.getBluetoothDevices API.

my.offBluetoothDeviceFound

Removes the listener for the new Bluetooth device discovery event.

Code example

my.offBluetoothDeviceFound();

Whether to pass a callback value

• If you do not pass a callback value, all listeners for this event are removed. The following code provides an example:

  my.offBluetoothDeviceFound();

• If you pass a callback value, only the corresponding listener is removed. The following code provides an example:

  my.offBluetoothDeviceFound(this.callback);

Bugs and tips

• Tip: To prevent multiple callbacks for the same event, call the off method to remove existing listeners before you call the on method.

my.onBLECharacteristicValueChange(callback)

Listens for characteristic value changes on a BLE device.

Input parameters

Callback return value

Code example

Page({
  onLoad() {
    this.callback = this.callback.bind(this);
    my.onBLECharacteristicValueChange(this.callback);
  },
  onUnload() {
    my.offBLECharacteristicValueChange(this.callback);
  },
  callback(res) {
    console.log(res);
  },
})

Bugs and tips

• Tip: To prevent multiple callbacks for a single event, call the off method to remove existing listeners before calling the on method.

my.offBLECharacteristicValueChange

Removes the listener for characteristic value changes on a BLE device.

Input parameters

The type is a callback function whose input parameter is an Object with the following properties:

Passing a callback value

• If you do not pass a callback value, all listeners for this event are removed. The following code provides an example:

  my.offBLECharacteristicValueChange();

• If you pass a callback value, only the corresponding listener is removed. The following code provides an example:

  my.offBLECharacteristicValueChange(this.callback);

Code example

Page({
  onLoad() {
    this.callback = this.callback.bind(this);
    my.onBLECharacteristicValueChange(this.callback);
  },
  onUnload() {
    my.offBLECharacteristicValueChange(this.callback);
  },
  callback(res) {
    console.log(res);
  },
})

my.onBLEConnectionStateChanged(callback)

Listens for BLE connection error events, including device loss and abnormal disconnections.

Input parameters

Callback return value

Code example

/* .acss */
.help-info {
  padding:10px;
  color:#000000;
}
.help-title {
  padding:10px;
  color:#FC0D1B;
}

// .json
{
    "defaultTitle": "Bluetooth"
}

<!-- .axml-->
<view class="page">
  <view class="page-description">Bluetooth API</view>
  <view class="page-section">
    <view class="page-section-title">Local Bluetooth adapter state</view>
    <view class="page-section-demo">
       <button type="primary" onTap="openBluetoothAdapter">Initialize Bluetooth</button>
       <button type="primary" onTap="closeBluetoothAdapter">Close local Bluetooth</button>
       <button type="primary" onTap="getBluetoothAdapterState">Get Bluetooth state</button>
    </view>

    <view class="page-section-title">Scan for Bluetooth devices</view>
    <view class="page-section-demo">
       <button type="primary" onTap="startBluetoothDevicesDiscovery">Start search</button>
       <button type="primary" onTap="getBluetoothDevices">All discovered devices</button>
       <button type="primary" onTap="getConnectedBluetoothDevices">All connected devices</button>
       <button type="primary" onTap="stopBluetoothDevicesDiscovery">Stop search</button>
    </view>

    <view class="page-section-title">Connect to a device</view>
    <view class="page-section-demo">
       <input class="input" onInput="bindKeyInput" type="{{text}}" placeholder="Enter the deviceId of the device to connect to"></input>
       <button type="primary" onTap="connectBLEDevice">Connect to device</button>
       <button type="primary" onTap="getBLEDeviceServices">Get device services</button>
       <button type="primary" onTap="getBLEDeviceCharacteristics">Get read/write characteristics</button>
       <button type="primary" onTap="disconnectBLEDevice">Disconnect from device</button>
    </view>

     <view class="page-section-title">Read and write data</view>
     <view class="page-section-demo">
       <button type="primary" onTap="notifyBLECharacteristicValueChange">Listen for characteristic value changes</button>
       <button type="primary" onTap="readBLECharacteristicValue">Read data</button>
       <button type="primary" onTap="writeBLECharacteristicValue">Write data</button>
       <button type="primary" onTap="offBLECharacteristicValueChange">Cancel characteristic value listener</button>
    </view>

     <view class="page-section-title">Other events</view>
     <view class="page-section-demo">
       <button type="primary" onTap="bluetoothAdapterStateChange">Local Bluetooth state change</button>
       <button type="primary" onTap="offBluetoothAdapterStateChange">Cancel local Bluetooth state listener</button>
       <button type="primary" onTap="BLEConnectionStateChanged">Bluetooth connection state change</button>
       <button type="primary" onTap="offBLEConnectionStateChanged">Cancel Bluetooth connection state listener</button>

    </view>

  </view>
</view>

// .js
Page({
  data: {
    devid: '0D9C82AD-1CC0-414D-9526-119E08D28124',
    serid: 'FEE7',
    notifyId: '36F6',
    writeId: '36F5',
    charid: '',
    alldev: [{ deviceId: '' }],
  },

  // Get the local Bluetooth adapter state
  openBluetoothAdapter() {
    my.openBluetoothAdapter({
      success: res => {
        if (!res.isSupportBLE) {
          my.alert({ content: 'Sorry, Bluetooth is not available on your phone.' });
          return;
        }
        my.alert({ content: 'Initialization successful!' });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },
  closeBluetoothAdapter() {
    my.closeBluetoothAdapter({
      success: () => {
        my.alert({ content: 'Bluetooth closed successfully!' });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },
  getBluetoothAdapterState() {
    my.getBluetoothAdapterState({
      success: res => {
        if (!res.available) {
          my.alert({ content: 'Sorry, Bluetooth is not available on your phone.' });
          return;
        }
        my.alert({ content: JSON.stringify(res) });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },

  // Scan for Bluetooth devices
  startBluetoothDevicesDiscovery() {
    my.startBluetoothDevicesDiscovery({
      allowDuplicatesKey: false,
      success: () => {
        my.onBluetoothDeviceFound({
          success: res => {
            // my.alert({content:'Listening for new devices'+JSON.stringify(res)});
            var deviceArray = res.devices;
            for (var i = deviceArray.length - 1; i >= 0; i--) {
              var deviceObj = deviceArray[i];
              // Match the target device by device name or broadcast data, then record the deviceID for later use
              if (deviceObj.name == this.data.name) {
                my.alert({ content: 'Target device found' });
                my.offBluetoothDeviceFound();
                this.setData({
                  deviceId: deviceObj.deviceId,
                });
                break;
              }
            }
          },
          fail: error => {
            my.alert({ content: 'Failed to listen for new devices' + JSON.stringify(error) });
          },
        });
      },
      fail: error => {
        my.alert({ content: 'Failed to start scan' + JSON.stringify(error) });
      },
    });
  },

  // Stop scanning
  stopBluetoothDevicesDiscovery() {
    my.stopBluetoothDevicesDiscovery({
      success: res => {
        my.offBluetoothDeviceFound();
        my.alert({ content: 'Operation successful!' });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },

  // Get connected devices
  getConnectedBluetoothDevices() {
    my.getConnectedBluetoothDevices({
      success: res => {
        if (res.devices.length === 0) {
          my.alert({ content: 'No connected devices!' });
          return;
        }
        my.alert({ content: JSON.stringify(res) });
        devid = res.devices[0].deviceId;
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },

  // Get all discovered devices
  getBluetoothDevices() {
    my.getBluetoothDevices({
      success: res => {
        my.alert({ content: JSON.stringify(res) });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },

  bindKeyInput(e) {
    this.setData({
      devid: e.detail.value,
    });
  },

  // Connect to a device
  connectBLEDevice() {
    my.connectBLEDevice({
      deviceId: this.data.devid,
      success: res => {
        my.alert({ content: 'Connection successful' });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },

  // Disconnect
  disconnectBLEDevice() {
    my.disconnectBLEDevice({
      deviceId: this.data.devid,
      success: () => {
        my.alert({ content: 'Disconnection successful!' });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },

  // Get the services of a connected device. This must be done while connected.
  getBLEDeviceServices() {
    my.getConnectedBluetoothDevices({
      success: res => {
        if (res.devices.length === 0) {
          my.alert({ content: 'No connected devices' });
          return;
        }
        my.getBLEDeviceServices({
          deviceId: this.data.devid,
          success: res => {
            my.alert({ content: JSON.stringify(res) });
            this.setData({
              serid: res.services[0].serviceId,
            });
          },
          fail: error => {
            my.alert({ content: JSON.stringify(error) });
          },
        });
      },
    });
  },

  // Get the charid of a connected device. This must be done while connected. (This filters for read and write characteristics.)
  getBLEDeviceCharacteristics() {
    my.getConnectedBluetoothDevices({
      success: res => {
        if (res.devices.length === 0) {
          my.alert({ content: 'No connected devices' });
          return;
        }
        this.setData({
          devid: res.devices[0].deviceId,
        });
        my.getBLEDeviceCharacteristics({
          deviceId: this.data.devid,
          serviceId: this.data.serid,
          success: res => {
            my.alert({ content: JSON.stringify(res) });
            // See the document for characteristic object properties. Match and record the read/write characteristics for later use.
            this.setData({
              charid: res.characteristics[0].characteristicId,
            });
          },
          fail: error => {
            my.alert({ content: JSON.stringify(error) });
          },
        });
      },
    });
  },

  // Read and write data
  readBLECharacteristicValue() {
    my.getConnectedBluetoothDevices({
      success: res => {
        if (res.devices.length === 0) {
          my.alert({ content: 'No connected devices' });
          return;
        }
        this.setData({
          devid: res.devices[0].deviceId,
        });
        my.readBLECharacteristicValue({
          deviceId: this.data.devid,
          serviceId: this.data.serid,
          characteristicId: this.data.notifyId,
          // 1. Android read service
          // serviceId:'0000180d-0000-1000-8000-00805f9b34fb',
          // characteristicId:'00002a38-0000-1000-8000-00805f9b34fb',
          success: res => {
            my.alert({ content: JSON.stringify(res) });
          },
          fail: error => {
            my.alert({ content: 'Read failed' + JSON.stringify(error) });
          },
        });
      },
    });
  },

  writeBLECharacteristicValue() {
    my.getConnectedBluetoothDevices({
      success: res => {
        if (res.devices.length === 0) {
          my.alert({ content: 'No connected devices' });
          return;
        }
        this.setData({
          devid: res.devices[0].deviceId,
        });

        my.writeBLECharacteristicValue({
          deviceId: this.data.devid,
          serviceId: this.data.serid,
          characteristicId: this.data.charid,
          // Android write service
          //serviceId:'0000180d-0000-1000-8000-00805f9b34fb',
          //characteristicId:'00002a39-0000-1000-8000-00805f9b34fb',
          value: 'ABCD',
          success: res => {
            my.alert({ content: 'Data written successfully!' });
          },
          fail: error => {
            my.alert({ content: JSON.stringify(error) });
          },
        });
      },
    });
  },
  notifyBLECharacteristicValueChange() {
    my.getConnectedBluetoothDevices({
      success: res => {
        if (res.devices.length === 0) {
          my.alert({ content: 'No connected devices' });
          return;
        }
        this.setData({
          devid: res.devices[0].deviceId,
        });

        my.notifyBLECharacteristicValueChange({
          state: true,
          deviceId: this.data.devid,
          serviceId: this.data.serid,
          characteristicId: this.data.notifyId,
          success: () => {

            // Listen for characteristic value changes
            my.onBLECharacteristicValueChange({
              success: res => {

                //  my.alert({content: 'Characteristic value changed: '+JSON.stringify(res)});
                my.alert({ content: 'Response data received = ' + res.value });
              },
            });
            my.alert({ content: 'Listener enabled successfully' });
          },
          fail: error => {
            my.alert({ content: 'Failed to enable listener' + JSON.stringify(error) });
          },
        });
      },
    });
  },
  offBLECharacteristicValueChange() {
    my.offBLECharacteristicValueChange();
  },

  // Other events
  bluetoothAdapterStateChange() {
    my.onBluetoothAdapterStateChange(this.getBind('onBluetoothAdapterStateChange'));
  },
  onBluetoothAdapterStateChange() {
    if (res.error) {
      my.alert({ content: JSON.stringify(error) });
    } else {
      my.alert({ content: 'Local Bluetooth state changed: ' + JSON.stringify(res) });
    }
  },
  offBluetoothAdapterStateChange() {
    my.offBluetoothAdapterStateChange(this.getBind('onBluetoothAdapterStateChange'));
  },
  getBind(name) {
    if (!this[`bind${name}`]) {
      this[`bind${name}`] = this[name].bind(this);
    }
    return this[`bind${name}`];
  },
  BLEConnectionStateChanged() {
    my.onBLEConnectionStateChanged(this.getBind('onBLEConnectionStateChanged'));
  },
  onBLEConnectionStateChanged(res) {
    if (res.error) {
      my.alert({ content: JSON.stringify(error) });
    } else {
      my.alert({ content: 'Connection state changed: ' + JSON.stringify(res) });
    }
  },
  offBLEConnectionStateChanged() {
    my.offBLEConnectionStateChanged(this.getBind('onBLEConnectionStateChanged'));
  },
  onUnload() {
    this.offBLEConnectionStateChanged();
    this.offBLECharacteristicValueChange();
    this.offBluetoothAdapterStateChange();
    this.closeBluetoothAdapter();
  },
});

Bugs and tips

• Tip: To prevent multiple callbacks for a single event, call the off method to remove previous listeners before calling the on method.

my.offBLEConnectionStateChanged

Removes the listener for BLE connection state changes.

Code example

my.offBLEConnectionStateChanged();

Is passing a callback value required?

• If you do not pass a callback value, all listeners for this event are removed. The following code provides an example:

  my.offBLEConnectionStateChanged();

• If you pass a callback value, only the corresponding listener is removed. The following code provides an example:

  my.offBLEConnectionStateChanged(this.callback);

Bugs and tips

• Tip: To prevent multiple callbacks for a single event, call the off method to remove previous listeners before calling the on method.

my.onBluetoothAdapterStateChange(callback)

Listens for changes in the local Bluetooth adapter state.

Input parameters

Callback return value

Code example

/* .acss */
.help-info {
  padding:10px;
  color:#000000;
}
.help-title {
  padding:10px;
  color:#FC0D1B;
}

// .json
{
    "defaultTitle": "Bluetooth"
}

<!-- .axml-->
<view class="page">
  <view class="page-description">Bluetooth API</view>
  <view class="page-section">
    <view class="page-section-title">Local Bluetooth adapter state</view>
    <view class="page-section-demo">
       <button type="primary" onTap="openBluetoothAdapter">Initialize Bluetooth</button>
       <button type="primary" onTap="closeBluetoothAdapter">Close local Bluetooth</button>
       <button type="primary" onTap="getBluetoothAdapterState">Get Bluetooth state</button>
    </view>

    <view class="page-section-title">Scan for Bluetooth devices</view>
    <view class="page-section-demo">
       <button type="primary" onTap="startBluetoothDevicesDiscovery">Start search</button>
       <button type="primary" onTap="getBluetoothDevices">All discovered devices</button>
       <button type="primary" onTap="getConnectedBluetoothDevices">All connected devices</button>
       <button type="primary" onTap="stopBluetoothDevicesDiscovery">Stop search</button>
    </view>

    <view class="page-section-title">Connect to a device</view>
    <view class="page-section-demo">
       <input class="input" onInput="bindKeyInput" type="{{text}}" placeholder="Enter the deviceId of the device to connect to"></input>
       <button type="primary" onTap="connectBLEDevice">Connect to device</button>
       <button type="primary" onTap="getBLEDeviceServices">Get device services</button>
       <button type="primary" onTap="getBLEDeviceCharacteristics">Get read/write characteristics</button>
       <button type="primary" onTap="disconnectBLEDevice">Disconnect from device</button>
    </view>

     <view class="page-section-title">Read and write data</view>
     <view class="page-section-demo">
       <button type="primary" onTap="notifyBLECharacteristicValueChange">Listen for characteristic value changes</button>
       <button type="primary" onTap="readBLECharacteristicValue">Read data</button>
       <button type="primary" onTap="writeBLECharacteristicValue">Write data</button>
       <button type="primary" onTap="offBLECharacteristicValueChange">Cancel characteristic value listener</button>
    </view>

     <view class="page-section-title">Other events</view>
     <view class="page-section-demo">
       <button type="primary" onTap="bluetoothAdapterStateChange">Local Bluetooth state change</button>
       <button type="primary" onTap="offBluetoothAdapterStateChange">Cancel local Bluetooth state listener</button>
       <button type="primary" onTap="BLEConnectionStateChanged">Bluetooth connection state change</button>
       <button type="primary" onTap="offBLEConnectionStateChanged">Cancel Bluetooth connection state listener</button>

    </view>

  </view>
</view>

// .js
Page({
  data: {
    devid: '0D9C82AD-1CC0-414D-9526-119E08D28124',
    serid: 'FEE7',
    notifyId: '36F6',
    writeId: '36F5',
    charid: '',
    alldev: [{ deviceId: '' }],
  },

  // Get the local Bluetooth adapter state
  openBluetoothAdapter() {
    my.openBluetoothAdapter({
      success: res => {
        if (!res.isSupportBLE) {
          my.alert({ content: 'Sorry, Bluetooth is not available on your phone.' });
          return;
        }
        my.alert({ content: 'Initialization successful!' });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },
  closeBluetoothAdapter() {
    my.closeBluetoothAdapter({
      success: () => {
        my.alert({ content: 'Bluetooth closed successfully!' });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },
  getBluetoothAdapterState() {
    my.getBluetoothAdapterState({
      success: res => {
        if (!res.available) {
          my.alert({ content: 'Sorry, Bluetooth is not available on your phone.' });
          return;
        }
        my.alert({ content: JSON.stringify(res) });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },

  // Scan for Bluetooth devices
  startBluetoothDevicesDiscovery() {
    my.startBluetoothDevicesDiscovery({
      allowDuplicatesKey: false,
      success: () => {
        my.onBluetoothDeviceFound({
          success: res => {

            // my.alert({content:'Listening for new devices'+JSON.stringify(res)});
            var deviceArray = res.devices;
            for (var i = deviceArray.length - 1; i >= 0; i--) {
              var deviceObj = deviceArray[i];

              // Match the target device by device name or broadcast data, then record the deviceID for later use
              if (deviceObj.name == this.data.name) {
                my.alert({ content: 'Target device found' });
                my.offBluetoothDeviceFound();
                this.setData({
                  deviceId: deviceObj.deviceId,
                });
                break;
              }
            }
          },
          fail: error => {
            my.alert({ content: 'Failed to listen for new devices' + JSON.stringify(error) });
          },
        });
      },
      fail: error => {
        my.alert({ content: 'Failed to start scan' + JSON.stringify(error) });
      },
    });
  },

  // Stop scanning
  stopBluetoothDevicesDiscovery() {
    my.stopBluetoothDevicesDiscovery({
      success: res => {
        my.offBluetoothDeviceFound();
        my.alert({ content: 'Operation successful!' });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },

  // Get connected devices
  getConnectedBluetoothDevices() {
    my.getConnectedBluetoothDevices({
      success: res => {
        if (res.devices.length === 0) {
          my.alert({ content: 'No connected devices!' });
          return;
        }
        my.alert({ content: JSON.stringify(res) });
        devid = res.devices[0].deviceId;
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },

  // Get all discovered devices
  getBluetoothDevices() {
    my.getBluetoothDevices({
      success: res => {
        my.alert({ content: JSON.stringify(res) });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },

  bindKeyInput(e) {
    this.setData({
      devid: e.detail.value,
    });
  },

  // Connect to a device
  connectBLEDevice() {
    my.connectBLEDevice({
      deviceId: this.data.devid,
      success: res => {
        my.alert({ content: 'Connection successful' });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },

  // Disconnect
  disconnectBLEDevice() {
    my.disconnectBLEDevice({
      deviceId: this.data.devid,
      success: () => {
        my.alert({ content: 'Disconnection successful!' });
      },
      fail: error => {
        my.alert({ content: JSON.stringify(error) });
      },
    });
  },

  // Get the services of a connected device. This must be done while connected.
  getBLEDeviceServices() {
    my.getConnectedBluetoothDevices({
      success: res => {
        if (res.devices.length === 0) {
          my.alert({ content: 'No connected devices' });
          return;
        }
        my.getBLEDeviceServices({
          deviceId: this.data.devid,
          success: res => {
            my.alert({ content: JSON.stringify(res) });
            this.setData({
              serid: res.services[0].serviceId,
            });
          },
          fail: error => {
            my.alert({ content: JSON.stringify(error) });
          },
        });
      },
    });
  },

  // Get the charid of a connected device. This must be done while connected. (This filters for read and write characteristics.)
  getBLEDeviceCharacteristics() {
    my.getConnectedBluetoothDevices({
      success: res => {
        if (res.devices.length === 0) {
          my.alert({ content: 'No connected devices' });
          return;
        }
        this.setData({
          devid: res.devices[0].deviceId,
        });
        my.getBLEDeviceCharacteristics({
          deviceId: this.data.devid,
          serviceId: this.data.serid,
          success: res => {
            my.alert({ content: JSON.stringify(res) });

            // See the document for characteristic object properties. Match and record the read/write characteristics for later use.
            this.setData({
              charid: res.characteristics[0].characteristicId,
            });
          },
          fail: error => {
            my.alert({ content: JSON.stringify(error) });
          },
        });
      },
    });
  },

  // Read and write data
  readBLECharacteristicValue() {
    my.getConnectedBluetoothDevices({
      success: res => {
        if (res.devices.length === 0) {
          my.alert({ content: 'No connected devices' });
          return;
        }
        this.setData({
          devid: res.devices[0].deviceId,
        });
        my.readBLECharacteristicValue({
          deviceId: this.data.devid,
          serviceId: this.data.serid,
          characteristicId: this.data.notifyId,

          // 1. Android read service
          // serviceId:'0000180d-0000-1000-8000-00805f9b34fb',
          // characteristicId:'00002a38-0000-1000-8000-00805f9b34fb',
          success: res => {
            my.alert({ content: JSON.stringify(res) });
          },
          fail: error => {
            my.alert({ content: 'Read failed' + JSON.stringify(error) });
          },
        });
      },
    });
  },

  writeBLECharacteristicValue() {
    my.getConnectedBluetoothDevices({
      success: res => {
        if (res.devices.length === 0) {
          my.alert({ content: 'No connected devices' });
          return;
        }
        this.setData({
          devid: res.devices[0].deviceId,
        });

        my.writeBLECharacteristicValue({
          deviceId: this.data.devid,
          serviceId: this.data.serid,
          characteristicId: this.data.charid,

          // Android write service
          //serviceId:'0000180d-0000-1000-8000-00805f9b34fb',
          //characteristicId:'00002a39-0000-1000-8000-00805f9b34fb',
          value: 'ABCD',
          success: res => {
            my.alert({ content: 'Data written successfully!' });
          },
          fail: error => {
            my.alert({ content: JSON.stringify(error) });
          },
        });
      },
    });
  },
  notifyBLECharacteristicValueChange() {
    my.getConnectedBluetoothDevices({
      success: res => {
        if (res.devices.length === 0) {
          my.alert({ content: 'No connected devices' });
          return;
        }
        this.setData({
          devid: res.devices[0].deviceId,
        });

        my.notifyBLECharacteristicValueChange({
          state: true,
          deviceId: this.data.devid,
          serviceId: this.data.serid,
          characteristicId: this.data.notifyId,
          success: () => {

            // Listen for characteristic value changes
            my.onBLECharacteristicValueChange({
              success: res => {

                //  my.alert({content: 'Characteristic value changed: '+JSON.stringify(res)});
                my.alert({ content: 'Response data received = ' + res.value });
              },
            });
            my.alert({ content: 'Listener enabled successfully' });
          },
          fail: error => {
            my.alert({ content: 'Failed to enable listener' + JSON.stringify(error) });
          },
        });
      },
    });
  },
  offBLECharacteristicValueChange() {
    my.offBLECharacteristicValueChange();
  },

  // Other events
  bluetoothAdapterStateChange() {
    my.onBluetoothAdapterStateChange(this.getBind('onBluetoothAdapterStateChange'));
  },
  onBluetoothAdapterStateChange() {
    if (res.error) {
      my.alert({ content: JSON.stringify(error) });
    } else {
      my.alert({ content: 'Local Bluetooth state changed: ' + JSON.stringify(res) });
    }
  },
  offBluetoothAdapterStateChange() {
    my.offBluetoothAdapterStateChange(this.getBind('onBluetoothAdapterStateChange'));
  },
  getBind(name) {
    if (!this[`bind${name}`]) {
      this[`bind${name}`] = this[name].bind(this);
    }
    return this[`bind${name}`];
  },
  BLEConnectionStateChanged() {
    my.onBLEConnectionStateChanged(this.getBind('onBLEConnectionStateChanged'));
  },
  onBLEConnectionStateChanged(res) {
    if (res.error) {
      my.alert({ content: JSON.stringify(error) });
    } else {
      my.alert({ content: 'Connection state changed: ' + JSON.stringify(res) });
    }
  },
  offBLEConnectionStateChanged() {
    my.offBLEConnectionStateChanged(this.getBind('onBLEConnectionStateChanged'));
  },
  onUnload() {
    this.offBLEConnectionStateChanged();
    this.offBLECharacteristicValueChange();
    this.offBluetoothAdapterStateChange();
    this.closeBluetoothAdapter();
  },
});

my.offBluetoothAdapterStateChange

Removes the listener for local Bluetooth state changes.

Code example

my.offBluetoothAdapterStateChange();

Whether to pass a callback value

• If you do not pass a callback value, all listeners for this event are removed. The following code provides an example:

  my.offBluetoothAdapterStateChange();

• If you pass a callback value, only the corresponding listener is removed. The following code provides an example:

  my.offBluetoothAdapterStateChange(this.callback);

Bugs and tips

• Tip: To prevent duplicate callbacks for an event, call the off method to remove any existing listeners before you call the on method.