Scanning for audio sink CBPeripheral possible?

I am trying to get the charactersics of an attached bluetooth audio sink in my app. Is this possible? I have not had any success with the following code:

- (void)startScanning
{
    self.bluetoothManager = [[CBCentralManager alloc] initWithDelegate:self queue:nil];
}

- (void)centralManagerDidUpdateState:(CBCentralManager *)central
{
    if (central.state == CBCentralManagerStatePoweredOn) {
        CBUUID *audioSink = [CBUUID UUIDWithString:@"110B"];
        [self.bluetoothManager scanForPeripheralsWithServices:@[ audioSink ] options:nil];
        [self.bluetoothManager retrieveConnectedPeripheralsWithServices:@[ audioSink ]];
    }
}

- (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI
{
    // Never calls back
}

- (void)centralManager:(CBCentralManager *)central didRetrieveConnectedPeripherals:(NSArray *)peripherals
{
     // Always empty
}

I am pretty sure the UUID is correct, lifted from here: https://www.bluetooth.org/en-us/specification/assigned-numbers/service-discovery

I have tried the code with and without bluetooth speakers paired, the only peripheral I can find is my laptop if I don't specify the service I am looking for. Does the system handle audio sinks differently?