AirPlay is one of the easiest ways to send media content from your Mac or iOS device to your Apple TV. However, it requires both the device as well as the Apple TV to first be on the same network. This is fine for when you’re at home but so convenient when you’re trying to show something on someone else’s Apple TV.
Apple has removed that limitation with the new iOS 8. Now, your device will connect directly to an Apple TV without having to connect first to the Wi-Fi network.