439614 Add advertising to iPhone app

I have an iPhone app that uses vertical view mode only. I want to place a spot for iAd banner and also a spot for AdMob banner when iAd cannot load. So basically, iAd will load each time, but if the user is in another country or iAd creates an error, then AdMob banner will load to replace it. This should be done properly using a view controller and conforming with apples iAd terms and conditions. This should not be hard for an experienced iPhone developer.