Admob SDK integration

- (void)requestRewardedAd {
   __weak ViewController *weakSelf = self;

  GADRequest *request = [GADRequest request];
  [GADRewardedAd
   loadWithAdUnitID:@"ad unit ID"
   request:request
   completionHandler:^(GADRewardedAd *ad, NSError *error) {
     self.rewardedAd = ad;
     self.rewardedAd.paidEventHandler = ^void(GADAdValue *_Nonnull value) {
        ViewController *strongSelf = weakSelf;
          // for more information, please check AdMob official docs at:
          // https://developers.google.com/admob/ios/impression-level-ad-revenue
          GADAdNetworkResponseInfo *loadedAdNetworkResponseInfo = strongSelf.rewardedAd.responseInfo.loadedAdNetworkResponseInfo;

          // send ad revenue info to Adjust
          ADJAdRevenue *adRevenue = [[ADJAdRevenue alloc]
                              initWithSource:@"admob_sdk"];
          [adRevenue setRevenue:value.value currency:value.currencyCode];
          [adRevenue setAdRevenueNetwork:loadedAdNetworkResponseInfo.adSourceName]
          [Adjust trackAdRevenue:adRevenue];
      }
    }
  ];
}