A little (free) step synth on the app store now. Here’s the description:
This is a step sequencer combined with a synthesizer. It simply plays the columns one by one at the speed you define in the settings page. The synthesizer is currently very limited the only option is the waveform. There are currently two waveforms included: a saw and a square wave. For the next release I’m planning on adding more control methods for the synthesizer.