This is a simple example of iAd integration using Swift. It creates a private singleton ADBannerView and a public function to add the banner to a view controller's view.
public func moveADBannerToViewController(viewController: UIViewController, atPosition position: ADBAnnerPosition)
It let you chose between .Top or .Bottom position for the banner inside the view controller's view.
The banner is just hidden in case there's no ad to show.
It is intended as just a simple example, but it might already cover the needs for most common iPhone use cases. Anyway it can be easily extended to other needs.