I was always missing simple solution for controling arduino based robots with an iOS device (iPhone, iPad). While on Android within minutes you can make simple application in App Inventor which will communicate over popular bluetooth modules such as HC-06 or HC-05, on iOS classic bluetooth is closed for homegrown developer.

Fortunately there is Bluetooth 4.0 (LE) and it has it`s HC-05/6 alternative with easy accesible HM-10 and HM-11 modules, and more fortunately they are BLE-to Serial converters so getting them talking to an Arduino board is simple.

I decided to make the app myself. I used UNITY engine to make it multiplatform. I used simple asset from Shatalmi to give the app bluetooth skills and creating UI with Unity new UI tools was a suprising pleasure.

You can find more info about the app and arduino code on:
http://www.eng.lofirobot.com/lofi-control/