Following its somewhat mysterious disappearance last month, Rogue Amoeba’s Airfoil Speakers Touch has reappeared on the App Store, with an updated version that removes the “Enhanced Receiving” in-app purchase option that allowed users to receive audio streamed natively over AirPlay from iTunes or another iOS device. With version 3.1 users can also now set the app to stay awake in order to remain available for streaming at all times; the keep awake setting is also enabled automatically when charging.
Rogue Amoeba first reported the removal of Airfoil Speakers Touch on May 24, indicating at the time that the company did not have a clear answer as to why Apple had chosen to remove the already-approved application, and that it believed Airfoil Speakers Touch to be “in full compliance with Apple’s posted rules and developer agreements.” Rogue Amoeba CEO Paul Kafasis later posted a follow-up on the company’s blog, indicating that Apple had told the company that the app was in violation of Apple’s rule stating that “applications may only use Documented APIs in the manner prescribed by Apple and must not use or call any private APIs” but had been unable to tell them which specific APIs were being misused. Kafasis goes on to address the speculation that the issue may have been the feature added in version 3.0 to receive audio natively from other AirPlay sources, but argues that the API rules should not apply as AirPlay is a network protocol and not an API. However, AirPlay is an encrypted network protocol requiring an AirPlay receiver to have an appropriate private key to decrypt the audio stream; although other developers have successfully reverse-engineered the Airport Express key to develop software-only AirPlay receivers, it is unclear what method Rogue Amoeba was using in their particular application. It is also worth noting, however, that manufactures of hardware devices such as AirPlay speakers are required to pay a licensing fee to Apple to use the technology; no such licensing program currently exists for software-only AirPlay implementations.