iAds application crashing on OS 3.0 - 3.2

how to set iAds so the a开发者_如何学JAVApplication does not crash on older OS (3.0 - 3.2)

I suppose you need to do 2 things (hope I haven't missed anything):

1. Link with iAd framework as 'weak': Target->Info->Linked Libraries -> Set library type as weak

2. Check if iAd classes are present in run-time before use them e.g.:

   Class adBannerClass = NSClassFromString(@"ADBannerView");
   if (adBannerClass)
       // Work with banner