a05b3497_iOS_Keys_Table_1_Summary_of_UIKit_keys_Summary
[Key] UISupportedExternalAccessoryProtocols [Xcode name] “Supported external accessory protocols” [Availability] iOS 3.0 and later [Summary] 
Specifies the communications protocols supported for communication with attached hardware accessories. See UISupportedExternalAccessoryProtocols for details.
iOS Keys