Dimos Gaidatzis released Pen2Bow, which is the most impressive musical use of the Apple Pencil I've seen yet. The app is a violin-styled MIDI controller that generates 4 MIDI CC messages based on the Pencil's position, tilt, and pressure. It sounds almost gimmicky, but the demo video is amazing!
Pen2Bow iTunes Description:Pen2Bow is a violin bow MIDI controller using the Apple Pencil on the iPad Pro. It recognizes linear as well as circular pencil motion and generates bow movement from the user input. Circular motion enables the infinite extension of the bow that otherwise would be limited in length. This frees the user from constantly thinking about performing bow changes in order to prevent the bow from running out. Intended bow changes are accurately recognized and included in the midi output. We are calling this type of device an infinity bow controller and believe it is one of the very few, if not the only practical MIDI input device for bowed instruments.
Pen2Bow takes full advantage of the sensors in the Apple Pencil and generates 4 continuous MIDI controllers: velocity, force, tilt and orientation. These can be used to drive virtual instruments such as violins or synthesizers. The software is optimized for minimal latency which amounts to about 10ms on the iPad Pro 10.5-inch and 12.9-inch(2.gen) and 20ms on the iPad Pro 9.7-inch and 12.9-inch(1.gen). Pen2Bow fully utilizes the high resolution positional information at 240Hz provided by the Apple Pencil to estimate robust bow velocities.
Folks have been trying to come up with designs for the "future of musical instruments" for a while now. We've seen some impressive and innovative efforts, like the Eigenharp. I think this app is on a more likely track. Very few people cared to learn the Eigenharp, because it was both weird and expensive. This looks simple and intriguing. I wonder if we'll see whole instruments designed around this concept in the future.