There are a few programs out on the web that allow developers to screen share or create training by showing something on the iPad or iPhone.
iTools is a free software that is installed on your Mac or PC. Your device will be tethered to your Mac or PC, and then it will be able to mirror on your screen.
Reflector is an app that costs $12.99. Reflector uses Airplay to connect with your Mac or PC. Your iPad or iPhone must be on the same wireless subnet connection as your PC.
Elgato is a device that costs around $179 and free software. Elgato is able to do much more than mirroring iPads and iPhones, which is why the cost of the device is high.