In reply to CruxProblem:
Mind if I ask how you're making the app? Java with the Eclipse Android plugin, using the iOS IDE, or web-based? (No technical insight here; just curious!)
I'd give each problem four categories, if it were me: type of holds (crimpy, slopy, simulated rock etc.), type of route (dyno-ey, technical, flexibility, strength, etc.), type of wall (cave, overhang, slab, highball etc.), and graded difficulty.
Maybe if I was being super-anal also whether I found it high or low for its grade, how many attempts I took, etc. etc..