Admob problems with IOS build

Hi all.

I have been experiencing problems with Admob in a 2D game in Unity. To simplify the issue, I created a new project with nothing but a basic script attached to main camera as follows:

 using UnityEngine;
  using System.Collections;
  using GoogleMobileAds.Api;
  
  public class AdMobScript : MonoBehaviour {
      
      void Start()
      {
          RequestBanner();
      }
  
  
      private void RequestBanner()
      {
          #if UNITY_ANDROID
              string adUnitId = "<my android adunitid goes here>";
          #elif UNITY_IPHONE
              string adUnitId = "<my ios adunitid goes here>";
          #else
              string adUnitId = "unexpected_platform";
          #endif
  
          // Create a 320x50 banner at the top of the screen.
          BannerView bannerView = new BannerView(adUnitId, AdSize.Banner, AdPosition.TopRight);
          // Create an empty ad request.
          AdRequest request = new AdRequest.Builder().Build();
          // Load the banner with the request.
          bannerView.LoadAd(request);
      }
  }

This is actually the basic example script given here: link text

except I change my adunitids with proper values while testing the script.

When I build the project for IOS, I get the following error:

 Could not create a new Xcode project with CocoaPods: Encountered unexpected error while running pod
 UnityEngine.Debug:LogWarning(Object)
 GoogleMobileAds.Postprocessor:RunPodUpdate(String) (at Assets/GoogleMobileAds/Editor/PostProcessor.cs:60)
 GoogleMobileAds.Postprocessor:OnPostprocessBuild(BuildTarget, String) (at Assets/GoogleMobileAds/Editor/PostProcessor.cs:27)
 

My Unity version is 5.3.6f1 Personal, Android Studio 2.1.2, Google Mobile Ads Unity Plugin v3.0.5 and on my console I get resolver version is 10102.

Upgrading Unity to 5.4.0f3 corrupted my project so that is not an option for now.

How can I debug this problem from here?