MiBeacon

Now use your iOS device as a Bluetooth Low Energy (BLE) beacon!
MiBeacon allows you to enter your desired UUID, Major, and Minor numbers on the settings screen.
That's all there is to it!
Also includes convenient on/off switch to enable or disable your beacon on the fly.
Enjoy!
NOTE: This app does NOT run in the background. In order for your beacon to continually transmit, you need to keep it in the foreground. If you want it to transmit indefinitely, simply place it in the foreground (i.e. run it), and make sure that when it's running you have previously disabled auto-lock (in iPhone settings under 'general') so the phone never goes to sleep. Then it will run forever as a beacon!