1) Were you in public?
2) Were you intoxicated?
The prosecution rests.
Not quite true as there are Iowa Supreme Court cases which say it may depend on WHY you were in a public space. For example, if an officer orders you to come out of your house, then you cannon be guilty of public intoxication, even though you may be intoxicated and were in a public place when arrested.
Based on the facts of your case, you may or may not have a defense. You should definitely talk to an attorney. I think you can do so for free if you're an ISU student at student legal services.