Helio Workstation - Cross-platform lightweight speed-painting tool for creating music.
Midi Studio - Full-featured, modular MIDI control surface for iOS
Sibelius - Sibelius is a virtual score creation tool which allows composers to easily create new piano scores, developed by Avid.
Navichord - Intuitive chord sequencer and MIDI controller for iOS
Guitar Pro 7 - Create, play and share your tabs
IsoPad - IsoPad lets you use your Windows tablet to play electronic MIDI instruments.