sonogrid (lowercase required!) is a simple and effective pattern sequencer for iOS from developer rCreativ.
The app is described on the App Store as a “Drum Machine on Steroids” but the possible ways sonogrid can be used are much wider.
It is definitely geared up for rhythmic experimentation. Each rhythmic pattern can be between 1 and 32 steps long with each pattern assigned a note. The note being sent for each pattern can be changed but currently you are not able to use multiple notes in a single pattern.
You can layer up to 16 patterns that can trigger the very basic internal sounds. The more creatively satisfying usage however is to send each pattern out via Midi to other music Apps or even hardware synths or desktop plugins.
The controls include intuitive mute, solo buttons per pattern.
You could use sonogrid as a straight 4/4 time signature 16 bar looping sequencer but the App excels where you deviate from this. sonogrid excels at polyrhythms – Steve Reich, anyone?
The way each pattern is laid out provides a very smart visual representation of the complexity of rhythm that is occurring. You can have 3 step, 8 step, 13 step and 17 step patterns looping together and each note lights up as it sounds. There are some great editing options to easily add/delete steps, double/halve the pattern. You can also randomize, shift the pattern left/right, invert (switch on/off value of notes) and flip (mirror image of pattern).
sonogrid has amazing potential for development and it seems the developer is planning on adding additional features over time including a key changer and Ableton Link. Top of my list would be adding the ability to have multiple notes in each pattern/track.
sonogrid is still new and at 99c is extremely good value for what it does. It allows you to experiment quickly and easily with anything from simple rhythmic patterns to complex and evolving polyrhythms and syncopated beats.