If you’re using the latest Apple devices and all your software is up to date, then your iPhone will now use Bluetooth to search for nearby AppleTVs as well as just searching on the network using Bonjour. The end result is the same – streaming over the local Wi-Fi network – but if you have an odd or non-standard Wi-Fi setup, this might help[,your devices talk to one another.
Apple TV Now Supports AirPlay With Bluetooth