Often when I'm not on the computer, comes some ideas about scripts or algorithms. I think it would be interesting make a software for mobile, something like monodevelop with all Unity3D libraries in which I can write my ideas and get the errors.
And what exactly do you request? Unity already supports developing for iOS and Android if you buy one of the mobile addon licenses, for over 2 years already and since Unity 3 you use Monodevelop for debugging the code, since unity 3.2 even on mobile through the connected remote debugger
there are a dozen programmer text editors on mobile to do exactly that. at least on iOS there are many and all suffering the same problem: that an onscreen keyboard is trash at best. the things he describes there are totally impossible for various reasons, including not legally allowed by apple and not reasonably possible anyway