kotlin mqtt发送回调

根据提供的引用内容，以下是一个Kotlin MQTT发送回调的示例：

private var callBack: MessageHandlerCallBack? = null

private class MessageHandlerCallBack : MqttCallback {
    override fun connectionLost(cause: Throwable?) {
        // 处理连接丢失的情况
    }

    override fun messageArrived(topic: String?, message: MqttMessage?) {
        // 处理接收到的消息
    }

    override fun deliveryComplete(token: IMqttDeliveryToken?) {
        // 处理消息发送完成的情况
    }
}

private fun setupMQTTManager(context: Context) {
    mContext = context
    clientid += MqttClient.generateClientId()

    // 创建MQTTManager实例
    mqttManager = MQTTManager()

    // 设置回调
    callBack = MessageHandlerCallBack()
    mqttManager?.setCallback(callBack)
}

private fun sendMessage(topic: String, message: String) {
    // 发送消息的逻辑
    // ...
}