How to use DeviceInformation.FindAllAsync to Enumerate all BLE devices visible to Windows Phone?

Question

1. I have a code to list all the BluetoothLE devices a Windows Phone 8.1 can detects (paired and unpaired):

       var devices = await DeviceInformation.FindAllAsync( BluetoothLEDevice.GetDeviceSelector() );
       foreach ( DeviceInformation di in devices )
           {
           BluetoothLEDevice bleDevice = await BluetoothLEDevice.FromIdAsync( di.Id );
   
           Debug.WriteLine( bleDevice.Name );
           }
   

However, the line:

var devices = await DeviceInformation.FindAllAsync( BluetoothLEDevice.GetDeviceSelector() );

Throws an exception.

Any Idea why?

2. I also tried this code:

   var devices = await DeviceInformation.FindAllAsync( GattDeviceService.GetDeviceSelectorFromUuid( GattServiceUuids.GenericAttribute ) );

This code doesn't throw an exception, but returns 0 devices.

Any Idea why?

In both case, the DeviceCapability is defined as follows:

    <m2:DeviceCapability Name="bluetooth.genericAttributeProfile">
        <m2:Device Id="any">
            <m2:Function Type="name:genericAttribute"/>
        </m2:Device>
    </m2:DeviceCapability>

Answer 1

If you are working with Windows Phone 8.1 you are not able to enumerate the non paired devices. This changes with Windows 10 SDK release 1511