MIDImorphosis is a universal iOS app that converts incoming sound into MIDI notes; it supports polyphonic pitch detection, so you can play chords and intervals on a guitar, and trigger notes on a synthesizer. You can also record MIDI notes with a DAW, allowing you to edit a performance later. The app also makes it easy to transcribe directly from your guitar to a tab application.
Traditional guitar to MIDI converters require a polyphonic pickup that is attached directly to the guitar; the pickup monitors each string independently. With the conventional guitar output, all the strings are mixed together — MIDImorphosis uses advanced signal processing algorithms to recover the individual notes.
The app supports Audiobus, can process recorded WAV files (with standard audio copy and paste support to import and export recordings), and has support for Core MIDI, Virtual MIDI, and DSMIDI WiFi. Pitch conversion is reasonably fast and accurate; the app is suitable for playing at moderate speeds — for shredding, we recommend hardware based systems.
Dock-based instrument adapters (Apogee Jam, Line 6 Sonic Port, iRig HD, and so), are recommended; headset based adapters frequently have a low frequency roll-off, preventing lower strings from being detected correctly.