Using a MacBook as an iOS “External Accessory"? Does Apple allow me to make an iOS app that uses a desktop/laptop computer as an external accessory? For example, using a computer to do external computation and/or send input events to the phone over the lightning connector cable. Technically I am not the manufacturer of these products but I was wondering whether Apple would allow such an app in the app store.
The old (pre-Lightling) connection "unofficially" supported a USB keyboard by plugging it into the Camera Connection Kit USB port. I not sure if this is still possible with the new Lightning port, although, some companies do make a Lightning-to-usb adapter.

Connecting the Keyboard this way lets you use it in any app that supports Bluetooth keyboards (which I think is pretty much any writing app). It does, however, show you a warning on screen when you connect the keyboard, but you can just dismiss it.

If you'd like to read more about what you could do with the Camera Connetion Kit USB port, check out the Using the CCK for more than just photography section of this article.



On a side note, you can also use you keyboard to fully control your iOS device by turning on some accessibility settings. I don't remember exactly what I used when I tried this, but it was either:

Settings &gt; General &gt; Accessibility &gt; Switch Control


or:

Settings &gt; General &gt; Accessibility &gt; VoiceOver   (just turn the sound off when you use it)




So in short, yes, you will be able to use you computer to control an app through the thunder connection, but depending on what you'd like to do, you may need to be a little clever about exactly how you implement this so you take advantage of some unofficial iOS features.

And, if this doesn't work for what you want, I know a lot of apps (like this one) connect to the PC via WiFi. These apps send commands to the PC, but I'm fairly sure you can make the connection go both ways as long as you don't need to control anything outside your own app.

Hope this helps!