I am developing an Apple TV app using OSX 10.11.1, Xcode 7.1.1, and iTunes 12.2.2.25. My Apple TV is a 3rd generation model.
My Apple TV is not detected by my iMac. It's also not detected by iTunes.
You need an Apple TV 4th generation to develop apps. The 3rd generation Apple TV is not supported by the new tvOS platform.