I made a simple app that let you chat between the RFduino BLE development platform and Macbook. This is my first project in Cocoa programming. It helped me to understand the mechanisms behind CoreBluetooth and how to interface with the RFduino. Maybe it is helpful for you as a reference on developing for the RFduino and CoreBluetooth.
This software is based on Apple Developer’s Heart Rate Monitor Example. I have not incorporated recent changes in CoreBluetooth (iOS7). Also interesting, this tutorial by the RFduino Team shows how to use the Nordic SDK with RFduino.