I'm working on an iphone/ipod app that will need to communicate with a computer (MAC for now, maybe PC if possible) though the USB dock connector cable. I'm a complete beginner with IPhone programming and from what I've been able to find out, the External Accessory framework is the place to start.
While going through the online documentation about the framework I came across references to supported protocols. I couldn't find any more information about them so I'm wondering what they mean by protocols? Are they well known ones like HTTP, FTP etc? or am I completely off the mark?
Thanks a lot
The External Accessory framework is for communication with custom hardware via the USB dock connector on the iPhone, or through Bluetooth. The device you are attempting to connect with must be part of the Made for iPod program, and must contain a chip that will decode the communication between the iPhone and the device.
The protocols referred to in the framework documentation are particular to each piece of hardware. The hardware manufacturer of, say, a game controller could set up a protocol for reading button presses or joystick movement. Any application which handled this protocol could then use that hardware accessory.
You will not be able to use the External Accessory framework to sync data via the USB connector. As Gerry suggests, you'll need to use WiFi or some other networking means to do so. In your previous question, Saurabh Sharan pointed out a hack for doing this through a tethered USB connection that the Cultured Code folks put together.
I think that is for custom devices. For communicating with computers, I would use Wi-Fi.
If you are syncing data with a Mac app, I would check out ZSync.
来源：https://stackoverflow.com/questions/2083453/what-are-the-protocols-supported-in-iphones-external-accessory-framework