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ROS 2 Subscriber

Sample Code

Here is the code for creating a python node that subscribes to /robot_news at 2Hz.

smartphone.py
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#!/usr/bin/env python

import rclpy
from rclpy.node import Node
from example_interfaces.msg import String

class SmartphoneNode(Node):

    def __init__(self):
        super().__init__("smartphone")
        self.subscriber_ = self.create_subscription(String, 'robot_news', self.callback_robot_news, 10)
        self.get_logger().info("Smartphone has been starte.")

    def callback_robot_news(self, msg):
        self.get_logger().info(msg.data)

def main (args=None):
    rclpy.init(args=args)
    node = SmartphoneNode()
    rclpy.spin(node)
    rclpy.shutdown()


if __name__ == '__main__':
    main()
smartphone.cpp
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#include "rclcpp/rclcpp.hpp"
#include "example_interfaces/msg/string.hpp"

class SmartphoneNode : public rclcpp::Node
{
public:
    SmartphoneNode() : Node("smartphone")
    {
        subscriber_ = this->create_subscription<example_interfaces::msg::String>(
                "robot_news", 10,
                std::bind(&SmartphoneNode::callbackRobotNews, this, std::placeholders::_1));
        RCLCPP_INFO(this->get_logger(), "Smartphone has been started.");
    }

private:
    void callbackRobotNews(const example_interfaces::msg::String::SharedPtr msg)
    {
        RCLCPP_INFO(this->get_logger(), "%s", msg->data.c_str());
    }
    rclcpp::Subscription<example_interfaces::msg::String>::SharedPtr subscriber_;
};


int main(int argc, char **argv)
{
    rclcpp::init(argc, argv);
    auto node = std::make_shared<SmartphoneNode>();
    rclcpp::spin(node);
    rclcpp::shutdown();
    return 0;
}