This is the slide deck and source code for a demonstration of Core Bluetooth that I presented at the Atlanta iOS Developer Meetup in March of 2014.
The keynote presentation in PDF format. Includes links to learning resources as well as the Bluetooth SIG standards that I used to create the heart rate monitor demo.
This is the xcode project that includes all of the demo source code. The demonstration code discovers a Bluetooth 4 (LE) peripheral that is advertising the Heart Rate Service. It then connects to the peripheral and begins retrieving the heart rate. You'll need an iOS device that supports Bluetooth 4 and you will need a Bluetooth 4 heart rate sensor. I used the Wahoo Fitness TICKR heart rate monitor but any heart rate monitor that complies with the Bluetooth specification should work. I've also tested the code with a Polar heart rate monitor. The code demonstrates the use of heart rate measurement, in contact indicator, and RR interval but does not do anything with the energy expended characteristic.