Can't seem to get data via subscribe feed

Hi this works great for pushing data to https://io.adafruit.com in my case. I'm trying to subscribe to a feed and get data from a feed.
If I want to let's say print the data from a subscribed feed, how do I go about doing that?
#include "MQTT.h"

void callback(char* topic, byte* payload, unsigned int length);

/**
 * if want to use IP address,
 * byte server[] = { XXX,XXX,XXX,XXX };
 * MQTT client(server, 1883, callback);
 * want to use domain name,
 * exp) iot.eclipse.org is Eclipse Open MQTT Broker: https://iot.eclipse.org/getting-started
 * MQTT client("iot.eclipse.org", 1883, callback);
 **/

SYSTEM_MODE(MANUAL);

//-----
#include "creds.h"
// please enter your sensitive data in creds.h
char ssid[] = SECRET_SSID;        // your network SSID (name)
char password[] = SECRET_PASS;    // your network password (use for WPA, or use as key for WEP)
int keyIndex = 0;            // your network key Index number (needed only for WEP)
//----

MQTT client("io.adafruit.com", 1883, callback);

// for QoS2 MQTTPUBREL message.
// this messageid maybe have store list or array structure.
uint16_t qos2messageid = 0;

// recieve message
void callback(char* topic, byte* payload, unsigned int length) {
      Serial.println("HERE");
    char p[length + 1];
    memcpy(p, payload, length);
    p[length] = NULL;

    if (!strcmp(p, "RED"))
        RGB.color(255, 0, 0);
    else if (!strcmp(p, "GREEN"))
        RGB.color(0, 255, 0);
    else if (!strcmp(p, "BLUE"))
        RGB.color(0, 0, 255);
    else
        RGB.color(255, 255, 255);
    delay(1000);
}

// QOS ack callback.
// if application use QOS1 or QOS2, MQTT server sendback ack message id.
void qoscallback(unsigned int messageid) {
    Serial.print("Ack Message Id:");
    Serial.println(messageid);
}

void setup() {
    Serial.begin(9600);

    // attempt to connect to Wifi network:
  Serial.print("Attempting to connect to Network named: ");
  // print the network name (SSID);
  Serial.println(ssid);

  // Connect to WPA/WPA2 network. Change this line if using open or WEP network:
  WiFi.on();
  WiFi.setCredentials(ssid, password);
  WiFi.connect();

  delay(200);
  while ( WiFi.connecting()) {
    // print dots while we wait to connect
    Serial.print(".");
    delay(300);
  }

  Serial.println("\nYou're connected to the network");
  Serial.println("Waiting for an ip address");

  IPAddress localIP = WiFi.localIP();
  while (localIP[0] == 0) {
    localIP = WiFi.localIP();
    Serial.println("waiting for an IP address");
    delay(1000);
  }

  Serial.println("\nIP Address obtained");

  delay(1000);

    RGB.control(true);

    // connect to the server
    client.connect("io.adafruit.com", IO_USERNAME, IO_KEY);

    // add qos callback. If don't add qoscallback, ACK message from MQTT server is ignored.
    client.addQosCallback(qoscallback);

    // publish/subscribe
    if (client.isConnected()) {
        delay(200);
        Serial.println("IN HERE");
        // get the messageid from parameter at 4.
        uint16_t messageid;
        client.publish("benjgorman/feeds/welcome-feed", "hello world QOS1", MQTT::QOS1, &messageid);
        Serial.println(messageid);

        // if 4th parameter don't set or NULL, application can not check the message id to the ACK message from MQTT server.
        client.publish("benjgorman/feeds/welcome-feed", "hello world QOS1(message is NULL)", MQTT::QOS1);

        // QOS=2
        client.publish("benjgorman/feeds/welcome-feed", "hello world QOS2", MQTT::QOS2, &messageid);
        Serial.println(messageid);

        // save QoS2 message id as global parameter.
        qos2messageid = messageid;

        // MQTT subscribe endpoint could have the QoS
        client.subscribe("benjgorman/feeds/servo", MQTT::QOS2);
    }

}

void loop() {
    if (client.isConnected())
    {
        client.loop();
        client.subscribe("benjgorman/feeds/servo", MQTT::QOS2);
    }
    else
    {
     Serial.println("Not Connected");
    }
    delay(5000);
}
hirotakaster / MQTT

Can't seem to get data via subscribe feed #82
