IK Multimedia iRig MIDI 2 Universal MIDI interface for iPhone/iPod touch/iPad and Mac/PC – Fleet Pro Sound
Minim - The iPhone Sized MIDI Controller - RouteNote Blog
How to use a USB MIDI Keyboard in GarageBand iOS (iPhone/iPad) - YouTube
IK Multimedia - iRig MIDI 2
iPhone to USB B Midi Cable 5FT, Lightning to USB 2.0 Midi Interface Cord for iPhone, iPad to Midi Controller, Electronic Music Instrument, Midi Keyboard, Recording Audio Interface and More | Walmart Canada
Amazon.com: Lightning to MIDI Cable for iPad/iPhone, [Apple MFi Certified] USB - B Midi Cord for Midi Controller, Electronic Music Instrument, Piano, Midi Keyboard, Recording Audio Interface, USB Microphone : Musical Instruments