Logging into iCloud on an Apple TV will register the set-top box as a potential remote access peer for the HomeKit application programming interface.
Once the user accepts using their Apple TV as a remote access peer, information from their connected home will automatically be synced with the TV accessory. This is made possible because HomeKit uses CloudKit to store home and accessory info in the cloud, while Keychain is used to store paired keys, the developer said.
Pete Deutschman 