10.2 Tokyo handles BLE discovery on Android differently than 10.1 Berlin.

(My apologies for this lengthy entry)

I have had some problems getting BLE to work according to my needs on both iOS and Android, but after some work arounds (see my comment and issues on quality.embarcadero.com: RSP 16891, 17763, and 17764) things have worked quite well (although BLE on iOS seems more stable than on Android).

Having switched to Tokyo, However, I have had to revise my handling of BLE device discovery, and I wonder if anyone else has noticed this change, if my original way of handling things (which was convenient) was fundamentally wrong, and/or if the behavior on Tokyo is as intended and by design or a bug.

In my application, I often need to "rediscover" a BLE device that was "defined" a long time ago (often in a previous app session). I handle this by storing the device name and MAC address so that I quickly can run discovery using a TBluetoothLEScanFilterList with the proper LocalName and DeviceAddress at some later point in time when I need to communicate with the device.

Using Berlin, I simply used a procedure like InitializeMyDevice below where BluetoothLE1 is a TBluetoothLE, FMyBleDevice is a TBluetoothLEDevice, and BluetoothLE1 has an OnDiscoverLEDevice = BluetoothLE1DiscoverLEDevice. Everything works fine: if the device is found, descovery stops immediately; if not, discovery times out.

Using Tokyo, however, the same code doesn't work:  

1. during Application.ProcessMessages the bleMainDiscoverLEDeviceis never called and the discovery always times out;

2. after timeout and exit of InitializeMyDevice all calls to bleMainDiscoverLEDeviceis do occur, but this is "too late".

Of course, this issue can be circumvented using, e.g., a second procedure to capture the result, but the "Berlin" method was quite simple and convenient.

So, hopefully some of you can have a look at the code below and explain to me what's going on!

Thanks in advance /Per

Code:

procedure BluetoothLE1DiscoverLEDevice(...)

begin

  // Double check

  if ((ADevice.DeviceName = MyDeviceName) and (ADevice.Address = MyMacAddress)) then

  begin

    FMyBleDevice := ADevice;

    BluetoothLE1.CancelDiscovery;

  end;

end;

function InitializeMyDevice: Boolean;

var

  LBleFilterList: TBluetoothLEScanFilterList;

  LBleFilter: TBluetoothLEScanFilter;

begin

  LBleFilterList := TBluetoothLEScanFilterList.Create;

  LBleScanFilter := TBluetoothLEScanFilter.Create;

  LBleScanFilter.LocalName := MyDeviceName;

  LBleScanFilterList.Add(LBleScanFilter);

  LBleScanFilter.DeviceAddress := MyMacAddress;

  LBleScanFilterList.Add(LBleScanFilter);

  try

    FMyBleDevice := nil;

    BluetoothLE1.DiscoverDevices(3000, LBleScanFilterList);

    while (FMyBleDevice = nil) do

       Application.ProcessMessages;

     Result := (FMyBleDevice = nil);

  finally

    LBleScanFilterList.Free;

  end;

end;