iOS: Block iAds by general category

I'd like to prevent ads of specific categories (e.g. "financial") to get displayed within my iOS app(s). On the iAd documentation I can't hardly find any solution how to do that. Also searching google / stack overflow did not brought up any solution.

Does anyone has a solution for me or is Apple's iAd program really that limited compared to admob? Or am I just searching at the wrong spots?

Thanks for helping me out :)