How to use ADBannerView?

i just added a ADBannerView to my view开发者_Python百科 using interface builder. There was no errors or warnings when i tried build and run. But when i reached the page containing ad banner the application crashed. Really i cant figure out whats happening. Should i add any code to make it run?

Are you weak linking the iAd framework for older devices? Have you added the delegate to your viewController?