I recently began working on an interface for Parable using a native iOS UI. At present it's still really rough in terms of UI, but it has finally reached a point where the core functionality is working.
I have considered running code on the device, but for now will use the server-side implementation of Parable instead. The Python implementation is already working nicely and is much better tested than the C implementation. And this avoids a bunch of battery drain, memory, and onboard performance issues. (Though it does present some issues with regards to bandwidth. A typical response set is around 500KiB in size).
So at this point I can launch it, enter code, and get a resulting stack. But there's a lot more that can be done. The server side response set includes a lot of other things (like the symbol table, memory maps, and a memory dump) that should be exposed via the client UI. My intention now is to finish the client side data parsing, refactor the view and model implementations, and then refine the interface into something that's substantially more pleasing to work with. Then I can start adding in other useful things, like a dictionary and memory view.
It also gives me a motivation to improve the server side. I really should cache the stuff that's not immediately needed (raw memory dump), and maybe allow for incremental modifications to a session so that each evaluation doesn't have to start from scratch.