External Accessory Command Protocol

Question

Could anyone tell me about the format of command bytes sent by the external accessory as per the declared protocol in the firmware of accessory and the info.plist of the iOS app code? I am aware that protocol name and bundle identifier name should be the same in the firmware and in the app code.

For example...

if(buf[0] == 0x10){Do something} , 0x10 

is the command byte sent by the external accessory when user presses button A on external accessory.

Who defines these command bytes, the manufacturer or is it dependent on the iOS app developer? Is there any way by which an iOS developer can know about these command bytes on the basis of protocol name if in case aceessory manufacturer does not provide it?

Answer 1

Late answer, but based on this answer to another question (specifically the first link), there is a set of generic commands which originated with the iPod and which (or some of which, at least) still apply to iPhone etc. Most of them obviously have to do with playing audio files.