Here is a repository of most RetroArch cores for iOS--Already compiled.
These are the cores that are missing:
3dengine bsnes_balanced bsnes_performance bsnes_mercury_balanced bsnes_mercury_performance mame mednafen_snes stonesoup testgl test
Please feel free to sumbit a pull request with these cores added.
Copy all cores to: RetroArch/apple/iOS/modules