Blynk appears to be a fairly put-together library for not only hooking up any Arduino or esp8266 to a phone through WiFi, but also through the net if desired. Install the app onto your iPhone or ...

You do need to set up the Arduino IDE to build for the ESP8266. That can vary by board, but here’s the instructions for the board I was using (from Adafruit; see below).

Android/iOS: If you want to control a Raspberry Pi or Arduino connected device from your phone, you’d usually need to know at least some programming.