UISupportedExternalAccessoryProtocols
The protocols that the app uses to communicate with external accessory hardware.
Discussion
Add this key to your app’s Info.plist file, and set the value to the names of the hardware protocols your app supports. You format protocol names as reverse-DNS strings. For example, the string “com.apple.myProtocol” might represent a custom protocol that Apple defines. Manufacturers can define custom protocols for their accessories or work with other manufacturers and organizations to define standard protocols for different accessory types.