BluePiano turns your iPhone or iPad into a virtual Bluetooth MIDI piano keyboard that can be used in other Bluetooth LE MIDI-capable apps. As soon as you launch the app, a Bluetooth MIDI service is advertised. Pressing keys on the keyboard sends standard MIDI events to any connected clients. You can perform two-finger swipes to scroll through octaves and enable or disable playthrough. BluePiano is the easiest way to use your iOS device as a MIDI piano keyboard for apps like GarageBand running on your Mac, for example.