Korg has announced a potentially useful little iOS interface known as the plugKey. Designed to get MIDI into your device and audio out of it, it also gives you the option to charge your iPhone or iPad while you're using it.
Connecting over a Lightning cable, the plugKey has a 5-Pin MIDI In port, while its L/Mono and R line outs are on 1/4-inch jacks. There's an additional 1/8-inch mini headphones jack and a micro USB port for charging, plus a volume knob.
What isn't on offer is an audio input or a USB MIDI port. If you want those, you'll have to look elsewhere.
The plugKey will work with all manner of music apps, obviously, but Korg is throwing in Le versions of its Module and Gadget apps to get you started. You'll be able to choose between black and white versions.
Find out more on the Korg website. The plugKey's price and release date are still to be confirmed.