Reads the current UV index level once per minute and publishes the value to PubNub when the value changes and at least once every 10 minutes. Code snippets for blog post. See project here: https://github.com/chandler767/PubNub-UV-Index-Monitor/

loop.ino

void loop() {
    sensorTimer = (sensorTimer + 1); // Add a second to the sensor timer.
    if (sensorTimer == 60) { // Check sensor.
      sensorTimer = 0; // Reset timer.
      sendTimer = (sendTimer + 1); // Add a minute to sendTimer. 
      if (sendTimer == 10) { // Reset timer after 10 minutes.
        sendTimer = 0; // Reset timer.
      }
      sensorValue = analogRead(A0); // Read sensor. Convert to UV index.
      if ((sensorValue >= 0) && (sensorValue < 20)) {
        uvindex = 0; 
      }
      else if ((sensorValue >= 20) && (sensorValue < 65)) {
        uvindex = 1;
      }
      else if ((sensorValue >= 65) && (sensorValue < 83)) {
        uvindex = 2;
      }
      else if ((sensorValue >= 83) && (sensorValue < 103)) {
        uvindex = 3;
      }
      else if ((sensorValue >= 103) && (sensorValue < 124)) {
        uvindex = 4;
      }
      else if ((sensorValue >= 124) && (sensorValue < 142)) {
        uvindex = 5;
      }
      else if ((sensorValue >= 142) && (sensorValue < 162)) {
        uvindex = 6;
      }
      else if ((sensorValue >= 162) && (sensorValue < 180)) {
        uvindex = 7;
      }
      else if ((sensorValue >= 180) && (sensorValue < 200)) {
        uvindex = 8;
      }
      else if ((sensorValue >= 200) && (sensorValue < 221)) {
        uvindex = 9;
      }
      else if ((sensorValue >= 221) && (sensorValue < 240)) {
        uvindex = 10;
      }
      else if (sensorValue >= 240) {
        uvindex = 11;
      }
      if ((lastuvindex != uvindex) || (sendTimer == 0)) { // Send a new message if sendTimer was reset or if UV index has changed.
        lastuvindex = uvindex; // Save the UV index.
        sendTimer = 0; // Reset timer.
        PubNub_BASE_CLIENT *client;
        Serial.println("publishing a message");
        char msg[64] = "{\"eon\":{\"uvindex\":"; 
        sprintf(msg + strlen(msg), "%d", uvindex);
        strcat(msg, "}}");
        client = PubNub.publish("uvindex", msg);
        if (!client) {
            Serial.println("publishing error");
            delay(1000);
            return;
        }
        while (client->connected()) {
            while (client->connected() && !client->available());
            char c = client->read();
            Serial.print(c);
        }
        client->stop();
        Serial.println();
      } 
    }
    delay(1000);
}

push-android.ino

if ((uvindex > 7) && (alertTimer == 0)) { // Send a push notification if the UV index is very high and no notification has been sent in the last 15 hours.
  alertTimer = 900; // Wait 15 hours before sending another push notification. 
  strcat(msg, "},\"pn_gcm\":{\"notification\":{\"body\":\"The UV index is very high. Avoid the sun.\"}}}");
} 
else {
  if (alertTimer > 0) {
    alertTimer = (alertTimer - 1); // Remove a minute from the alertTimer.
  }
  strcat(msg, "}}");
}

push-ios.ino

if ((uvindex > 7) && (alertTimer == 0)) { // Send a push notification if the UV index is very high and no notification has been sent in the last 15 hours.
  alertTimer = 900; // Wait 15 hours before sending another push notification. 
  strcat(msg, "},\"pn_apns\":{\"aps\":{\"alert\":\"The UV index is very high. Avoid the sun.\"}}}");
} 
else {
  if (alertTimer > 0) {
    alertTimer = (alertTimer - 1); // Remove a minute from the alertTimer.
  }
  strcat(msg, "}}");
}

sensor.ino

#include <ESP8266WiFi.h>
#define PubNub_BASE_CLIENT WiFiClient
#include <PubNub.h>
 
const static char ssid[] = "Sensor Network";
const static char pass[] = "sens0rpassw0rd";

int sendTimer;   // Timer used to control how often messages are published. Sends a new message once every 10 minutes.
int sensorTimer; // Timer used to control how often sensor is checked. Checked every 60 seconds.
float sensorValue; // Value from sensor.
int lastuvindex; // UV index on previous loop.
int uvindex; // Value from sensor converted to UV index.

setup.ino

void setup() {
    Serial.begin(9600);
    WiFi.begin(ssid, pass);
    if(WiFi.waitForConnectResult() == WL_CONNECTED){
        Serial.println("WiFi connected.");
        PubNub.begin("pub-key", "sub-key");
    } else {
        Serial.println("Couldn't get a wifi connection.");
        while(1) delay(100);
    }
}

For more info: https://github.com/chandler767/PubNub-UV-Index-Monitor/