BLEDeviceConnection.kt

// The saved list of services. The BluetoothGattService objects here can be used
// to list the characteristics in each service.
private var services: List<BluetoothGattService> = emptyList()

@RequiresPermission(PERMISSION_BLUETOOTH_CONNECT)
fun discoverServices() {
    gatt?.discoverServices()
}

private val callback = object: BluetoothGattCallback() {
    //Continuing our override of methods in this object from previous steps...
    ...

    override fun onServicesDiscovered(gatt: BluetoothGatt, status: Int) {
        super.onServicesDiscovered(gatt, status)
        services = gatt.services
    }
}