Hi! I would like to use Blynk to connect a sensor to an iphone, I am thinking of using a Arduino UNO board and a ReadBear NANo bluetooth module, is this going to work? Has anybody ever made something similar with Blynk before? Thanks!
Search this forum for the keyword RedBear Nano (works best if spelt correctly 
) … along with Bluetooth and whatever else you wish to look up.
But you will probably be better off starting with an ESP8266 WiFi based development board like the NodeMCU or Wemos D1 Mini.