I've hooked up the HM-12 Bluetooth 4.0 module (cheap Bluetooth module sold on Ebay and lots of other places) to an Arduino Nano. This module id designed to talk to both android and apple devices.
All I need is a simple serial terminal to send/receive data to the arduino from an apple/android phone.
For android, I used an app called BlueTerm, which works great. There are at least a dozen similar apps available in the google play store.
For Apple, there is nothing. There is an app called LightBlue which is sort of a bluetooth diagnostic tool. I was able to send individual characters/data back and forth from my iPhone5 and iPad3 to the android. So the hardware works fine.
I've searched high and low for a simple bluetooth serial terminal app for apple and can't find anything. Does anyone know of such an app? I'll even pay the $100 to put it up in the app store if you've got one.