I want to build an app for my iphone.  It's a simple app - an app to help you score NRA bullseye targets.  Searching the apple app store, there are apps that claim to be able to read your target (which I doubt, at least when it comes to rounds touching each other and what not) and apps that will help you log your cumalitive scores.  

I want to build something that I can walk up to the target to, enter the number of "X", "10", "9", "8", etc. into and have it keep track as I move through the courses of fire and calculate the score at the end.  

Is this even possible for average dude on average laptop to accomplish? Software wise? Skill wise?