Transposer MIDI plug-in in Logic Pro for iPad
The Transposer MIDI plug-in can transpose incoming MIDI notes in real time and can correct notes to a selected scale.

Transposer parameters
Transpose slider and field: Transpose incoming MIDI Notes by ± 24 semitones.
Retrigger Held Notes button: Retrigger held MIDI Notes when parameter changes are made.
Processing Order buttons: Transpose incoming MIDI Notes before or after applying the value set with the Scale Type pop-up menu or a User scale set with the Keyboard.
Note pop-up menu: Choose the root note for the scale.
Scale Type pop-up menu: Choose one of several preset scales or create your own custom scale (User) with the onscreen Keyboard.
Keyboard: Tap notes to turn them on or off. Notes that are turned off are excluded from the User scale.
Download this guide: PDF