WHAT: What is Bluetooth Low Energy (Bluetooth LE)? What is it used for? What is a peripheral and a central? What are services and characteristics, in the context of Bluetooth LE?
WHY: Why is Bluetooth LE so popular? Why should you, an iOS developer, be interested in learning more about how to interface with devices via Bluetooth LE?
HOW: How does the iOS CoreBluetooth framework work? How do I make my code testable while the device I need to interface with isn't ready yet?