Shared iAd on Tabbed Application

New to iOS development and I have a tabbed app with 4 tabs. I have an iAd showing on one tab and I don't want to regurgetate the code on every view controller and I know this is not the correct way to implement anyway. I have looked at the Apple code here and I'm struggling to be honest.

http://ift.tt/1hw3yBt

I have included the BannerViewController.m and BannerViewController.h in my application but I'm not fully sure how to get it to run the ad on each view controller.

Yours confused

JKX