Today, I completed the last pieces of the editing levels puzzle for my C++ port of Rainbow.
The first of these was level loading and saving (which doesn't really have a screenshot representation). The second was level selection:
This is a utilitarian screen designed for use when editing levels. Tapping any level edits it, tapping a '+' spot edits a new blank level.
One final thing I might add add to the editor is some sort of zoom capability (or I could forgo editing large levels on iPhone). The downside of this is it might encourage the creation of levels with detail too small to play on one screen; and I'd rather avoid having to have zoom during play, given that the rainbow's trail is accumulated into a framebuffer.