iAd shown below UITabBarController, on screen all the time?

I'd like to add an iAd bannerView below a UITabBarController. Preferably, the actual Tab Bar would stay the same size, moving up and down with the banner view, and the views for each tab would be resized.

Is this possibl开发者_运维知识库e or even allowed? If so, how would I go about doing this? Any tutorial links are appreciated.

If I had this setup, would I have resizing issues with the UINavigationControllers and their subviews?

Here is the technique I use, albeit for UINavigationController not UITabBarController. But I'm fairly certain you could make it work for a root UITabBarController.

global ADBannerView in iPhone app

While not mentioned in the SO question/answer, I do animate the ad appearing and disappearing, resizing the content view in the process. I've had no issues with this, and Apple's approved 3 apps with this code.