广告无法加载时隐藏在Swift中的iAd ADBannerView - 没有委托或委托没有实现didFailToReceiveAdWithError

This is the code I am using:

这是我正在使用的代码:

var bannerView = ADBannerView()
self.canDisplayBannerAds = true

//show ad banner if an ad loads
func bannerViewDidLoadAd(banner: ADBannerView!)
{bannerView.hidden = false}

//hide ad banner if the ad fails to load
func bannerViewFailsToLoadAd(banner: ADBannerView!,didFailToReceiveAdWithError error: NSError!)
{bannerView.hidden = true
 println("failed to receive ad")}
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