Are there any shooters on the iPhone with multiplayer that has a ranking system where u get xp for kills and get to different ranks like sergeant etc. and stuff like that?
How about that sniper game by Com2us? Your ranking goes down really fast unless you keep killing though. It's more of a find waldo than a shooter.
EXO Planet has that but since your rank keeps going up as you play longer, no matter whether you're actually good I don't think it's a good measure of skill.
Archetype has exactly that, it's currently only avaliable in some euro countries though, and is expected to have a worldwide rollout eventually.