title: How to make the interstitial ads load and appear on the app's UI? no respond in Xcode10
body: <p>I'm trying to load an interstitial ad in my app by integrating Firebase. when I click on "IBAction button" I am supposed to get an advertisement. But I get no response at all and don't see any ads on the screen.</p>
  
  <p>Xcode console shows the below message:
  1-[I-ACS037005] Unable to fetch effective App ID from identity
  2- You are currently using version 7.37.0 of the SDK. Please consider updating your SDK to the most recent SDK version to get the latest features and bug fixes. The latest SDK can be downloaded from...etc</p>
  
  <p>and this is my code:- </p>
  
  <pre><code>var interstitial: GADInterstitial!
  
  @IBAction func rewardedAdBtn(_ sender: Any) {
  
      interstitial = GADInterstitial(adUnitID: "/6499/example/interstitial")
      let request = GADRequest()
      //request.testDevices = [ kGADSimulatorID, "2077ef9a63d2b398840261c8221a0c9b" ]
  
      interstitial.load(request)
  }
  </code></pre>
  
  <p>I added two helpful functions the first one got "printed" but the second isn't !!</p>
  
  <pre><code>    /// Tells the delegate an ad request succeeded.
  func interstitialDidReceiveAd(_ ad: GADInterstitial) {
      print("interstitialDidReceiveAd")
  }
  
  
  /// Tells the delegate that an interstitial will be presented.
  func interstitialWillPresentScreen(_ ad: GADInterstitial) {
      print("interstitialWillPresentScreen")
  }
  </code></pre>