A super easy to use library for adding AdMob ads to Xamarin.Android, Xamarin.iOS, and MonoGame apps.
Add the nuget package located at: https://www.nuget.org/packages/AdMobBuddy/
Initialize the library in your Activity class:
//first param is an Activity
IAdManager ads = new AdMobAdapter(this, "your AdMob app ID", "your AdMob interstitial ad unit ID", "your Admob rewarded video ad unit ID"
Initialize the library: (in MonoGame, add this in your UIApplicationDelegate class)
//the first param is a UIViewController
IAdManager ads = new AdMobAdapter(game.Services.GetService<UIViewController>(), "your AdMob interstitial ad unit ID", "your Admob rewarded video ad unit ID"
Add your AdMob app ID to the info.plist file:
<key>GADApplicationIdentifier</key>
<string>your AdMob app ID</string>
Display an ad:
ads.DisplayInterstitialAd();
Display an ad and listen for the reward:
ads.OnVideoReward += VideoReward;
ads.DisplayRewardedVideoAd();
profit
If you still have any questions, there is a full-blown functioning app example at: https://github.com/dmanning23/RevMobBuddySample