External Accessory Framework Reference

The External Accessory framework provides support for communicating with external hardware connected to an iOS-based device through the 30-pin dock connector or wirelessly using Bluetooth. Applications that support external accessories must be sure to configure their Info.plist file correctly. Specifically, you must include the UISupportedExternalAccessoryProtocols key to declare the specific hardware protocols your application supports. For more information about this framework, see External Accessory Programming Topics.