iOS external accessory power

I'm trying to create an app which powers an exte开发者_C百科rnal accessory but I am not sure how to do it. Any hints or ideas?

All i plan on doing right now is have a UIView app that sends power to an external accessory.

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Is this something that you would even code?

I would have thought that you just have a small amount of power to the device, regardless of the software running on the iphone/ipad/itouch.

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That's going to be tricky and probably not in the scope of coding. First, you'd probably need to be a member of the Apple Made For iPhone (MFi) program and have to build your device to work in those specs.

Then you'd need to have the iOS device become the master USB device and your device become a slave (if I remember my USB controller configurations correctly - it's been 6 years).

But your first step is to get into the MFi program.

http://developer.apple.com/programs/mfi/