Double Decker for iOS will be available shortly.
The app lets you trigger notes and chords using an ordinary Bluetooth keyboard.
The keyboard is arranged in two different ways. First is a “piano style” layout, with a traditional piano keyboard on the two middle rows, a row with the ZXCV keys, and then a row for the number keys and punctuation. Each group of keys can have its own Soundfont or MIDI assignment, and each key is configurable for a single note, or a chord. The second arrangement consists of four 4×4 grids, which are also fully configurable.
Because of how iOS handles keyboards, the app will need to run in the foreground — but it can send notes to MIDI apps in the background. The app also features Apollo MIDI over Bluetooth; one way we expect many people to use the app is by running the keyboard connection through an iPhone, with MIDI notes being sent to an iPad — this gives you full screen access to synthesizers and sequencers, increases the playing surface area dramatically, and provides a powerful and configurable MIDI control environment.
And of course, the app is universal, and supports Audiobus.