Well, it is $0.99 until the 31st of May, but there’s also an iAP for $4.99 if you want MIDI in there. Here’s the app description:
A New Musical Instrument for Controlling Arpeggios with the Touch of a Finger.
Arpeggionome for iPhone transforms your iPhone into a new and expressive musical instrument. Design intricate patterns of musical notes, then trigger those patterns at different pitches and speeds with an x-y matrix. Tilt the iPhone for accelerometer-controlled pitchbend and volume, and with the MIDI Upgrade in-app purchase, control other iOS MIDI apps, external MIDI gear, and computer software like never before.
MUSICAL EXPRESSION AT 240 NOTES-PER-SECOND
- Move up-and-down the matrix to set the pattern’s rate
- Move left-and-right to set the pattern’s starting-note.
ACCELEROMETER-CONTROLLED PITCHBEND AND VOLUME, ESSENTIAL FOR 8-BIT SOLOS.
- Tilt the iPhone forward-and-back to control volume.
- Tilt the iPhone left-and-right to control pitchbend
DESIGN AN ARPEGGIO-PATTERN FROM SCRATCH…
- Fifteen pattern-parameters accessed on one page of touch-knobs
- Parameters include Key, Scale, Number of Notes, Step Distance, Notes Style, Alignment, Octave Range, Octave Style, Rates, Octave Offset, Note Offset, Velocity, Gate, and Tempo.
…OR USE A PRESET.
- Includes a Pattern Library with a wide selection of presets.
- Save and recall your own patterns.
- 8 pattern-buttons and 2 arrow-buttons provide quick access to the Pattern Library, enabling you to change and save patterns on the fly.
A ROCK-SOLID MIDI IMPLEMENTATION
- $4.99 In-App purchase required
- Control other iOS MIDI Applications (such as GarageBand, Animoog, Magellan Jr., and FunkBox).
- Control external MIDI devices (such hardware synthesizers, drum machines, and sound modules).
- Control computer software (such as Ableton Live, Logic, and Pro Tools)
- Send MIDI through Virtual MIDI, CoreMIDI hardware interfaces, or over WiFi or Bluetooth.
EVEN MORE FEATURES…
- A simple built-in synthesizer.
- Beautiful and informative visual feedback.
- Integrated documentation for every parameter and setting.
- Backup, restore, and transfer patterns between devices via iTunes File Sharing.