title: How to make a single shared instance of iAd banner throughout many view controllers?
body: <p>I have tried using a singleton class in my app delegate but I haven't been able to get that to work.  I've also checked out the iAdSuite examples (particularly the containerBanner example because it seemed to be the most relative) but I can't figure it out.  If there's a better way to accomplish this without using a singleton class and you can point me in the right direction I'd really appreciate it.  Some of my singleton class code is below.  Thank you!</p>
  
  <pre><code>@interface App Delegate
  
  @property (assign) iAdController *iadc;
  + (AppDelegate*) sharedApplication;
  - (iAdController*)sharedAd;
  @end
  
  @implementation AppDelegate
  
  @synthesize iadc;
  
  + (AppDelegate*) sharedApplication
  {
  return [[UIApplication sharedApplication] delegate];
  }
  
  -(iAdController*)sharedAd
  {
      if(iadc==nil){
          iadc=[iAdController new];
      }
      return iadc;
  }
  
  
  @interface ViewController
  
  iAdController*iadc=[[AppDelegate sharedApplication] sharedAd];
  //here i get an error saying, "initializer element is not a compile-time constant.
  </code></pre>
  
  <p>Everything is imported correctly.  If there's anything else I should post let me know.</p>