android - Since marshmallow update Bluetooth discovery using BluetoothAdapter.getDefaultAdapter().startDiscovery(); is broken

Question

I have an app using bluetooth and connecting to devices, can'f find any devices using BluetoothAdapter.getDefaultAdapter().startDiscovery(); It worked fine just before discovery. Tried also other apps, it doesn't work in other apps as well. But the device I try to pair (Arduino bt-module) can be found in Android settings. Any idea what could I try? I implemented everything like described on http://developer.android.com/guide/topics/connectivity/bluetooth.html and it worked before the update.

Answer 1

Bluetooth Adapter has been change in Android 6.0

You need to set the permission ACCESS_FINE_LOCATION or ACCESS_COARSE_LOCATION permission and need to use BluetoothLeScanner.startScan() method to start the scan.

Below is the description from change logs:

To provide users with greater data protection, in Android 6.0, Android removes programmatic access to the device’s local hardware identifier for apps using the Wi-Fi and Bluetooth APIs. The WifiInfo.getMacAddress() and the BluetoothAdapter.getAddress() methods now return a constant value of 02:00:00:00:00:00.

To access the hardware identifiers of nearby external devices via Bluetooth and Wi-Fi scans, your app must now have the ACCESS_FINE_LOCATION or ACCESS_COARSE_LOCATION permissions:

WifiManager.getScanResults()
BluetoothDevice.ACTION_FOUND
BluetoothLeScanner.startScan()

Note: When a device running Android 6.0 (API level 23) initiates a background Wi-Fi or Bluetooth scan, the operation is visible to external devices as originating from a randomized MAC address.

You can get more details from this link : http://developer.android.com/about/versions/marshmallow/android-6.0-changes.html