Interstitial ads

Interstitial ads are full-screen ads that cover the interface of their host app. They're typically displayed at natural transition points in the flow of an app, such as during the pause between levels in a game. When an app shows an interstitial ad, the user has the choice to either tap on the ad and continue to its destination or close it and return to the app. Case study.

This guide explains how to integrate interstitial ads into a Unity app.

Prerequisites

• Complete the Get started guide.

Always test with test ads

The following sample code contains an ad unit ID which you can use to request test ads. It's been specially configured to return test ads rather than production ads for every request, making it safe to use.

However, after you've registered an app in the AdMob web interface and created your own ad unit IDs for use in your app, explicitly configure your device as a test device during development.

Initialize the Mobile Ads SDK

Before loading ads, have your app initialize the Mobile Ads SDK by calling MobileAds.Initialize(). This needs to be done only once, ideally at app launch.

using GoogleMobileAds;
using GoogleMobileAds.Api;

public class GoogleMobileAdsDemoScript : MonoBehaviour
{
    public void Start()
    {
        // Initialize the Google Mobile Ads SDK.
        MobileAds.Initialize((InitializationStatus initStatus) =>
        {
            // This callback is called once the MobileAds SDK is initialized.
        });
    }
}

If you're using mediation, wait until the callback occurs before loading ads as this will ensure that all mediation adapters are initialized.

Implementation

The main steps to integrate interstitial ads are:

1. Load the interstitial ad
2. Show the interstitial ad
3. Listen to interstitial ad events
4. Clean up the interstitial ad
5. Preload the next interstitial ad

Load the interstitial ad

Loading an interstitial ad is accomplished using the static Load() method on the InterstitialAd class. The load method requires an ad unit ID, an AdRequest object, and a completion handler which gets called when ad loading succeeds or fails. The loaded InterstitialAd object is provided as a parameter in the completion handler. The example below shows how to load an InterstitialAd.

  // These ad units are configured to always serve test ads.
  #if UNITY_ANDROID
  private string _adUnitId = "ca-app-pub-3940256099942544/1033173712";
    #elif UNITY_IPHONE
  private string _adUnitId = "ca-app-pub-3940256099942544/4411468910";
    #else
  private string _adUnitId = "unused";
    #endif

  private InterstitialAd _interstitialAd;

  /// <summary>
  /// Loads the interstitial ad.
  /// </summary>
  public void LoadInterstitialAd()
  {
      // Clean up the old ad before loading a new one.
      if (_interstitialAd != null)
      {
            _interstitialAd.Destroy();
            _interstitialAd = null;
      }

      Debug.Log("Loading the interstitial ad.");

      // create our request used to load the ad.
      var adRequest = new AdRequest();

      // send the request to load the ad.
      InterstitialAd.Load(_adUnitId, adRequest,
          (InterstitialAd ad, LoadAdError error) =>
          {
              // if error is not null, the load request failed.
              if (error != null || ad == null)
              {
                  Debug.LogError("interstitial ad failed to load an ad " +
                                 "with error : " + error);
                  return;
              }

              Debug.Log("Interstitial ad loaded with response : "
                        + ad.GetResponseInfo());

              _interstitialAd = ad;
          });
  }

Show the interstitial ad

To show a loaded interstitial ad, call the Show() method on the InterstitialAd instance. Ads may be shown once per load. Use the CanShowAd() method to verify that the ad is ready to be shown.

/// <summary>
/// Shows the interstitial ad.
/// </summary>
public void ShowInterstitialAd()
{
    if (_interstitialAd != null && _interstitialAd.CanShowAd())
    {
        Debug.Log("Showing interstitial ad.");
        _interstitialAd.Show();
    }
    else
    {
        Debug.LogError("Interstitial ad is not ready yet.");
    }
}

Listen to interstitial ad events

To further customize the behavior of your ad, you can hook into a number of events in the ad's lifecycle. Listen for these events by registering a delegate as shown below.

private void RegisterEventHandlers(InterstitialAd interstitialAd)
{
    // Raised when the ad is estimated to have earned money.
    interstitialAd.OnAdPaid += (AdValue adValue) =>
    {
        Debug.Log(String.Format("Interstitial ad paid {0} {1}.",
            adValue.Value,
            adValue.CurrencyCode));
    };
    // Raised when an impression is recorded for an ad.
    interstitialAd.OnAdImpressionRecorded += () =>
    {
        Debug.Log("Interstitial ad recorded an impression.");
    };
    // Raised when a click is recorded for an ad.
    interstitialAd.OnAdClicked += () =>
    {
        Debug.Log("Interstitial ad was clicked.");
    };
    // Raised when an ad opened full screen content.
    interstitialAd.OnAdFullScreenContentOpened += () =>
    {
        Debug.Log("Interstitial ad full screen content opened.");
    };
    // Raised when the ad closed full screen content.
    interstitialAd.OnAdFullScreenContentClosed += () =>
    {
        Debug.Log("Interstitial ad full screen content closed.");
    };
    // Raised when the ad failed to open full screen content.
    interstitialAd.OnAdFullScreenContentFailed += (AdError error) =>
    {
        Debug.LogError("Interstitial ad failed to open full screen content " +
                       "with error : " + error);
    };
}

Clean up the interstitial ad

When you are finished with an InterstitialAd, make sure to call the Destroy() method before dropping your reference to it:

_interstitialAd.Destroy();

This notifies the plugin that the object is no longer used and the memory it occupies can be reclaimed. Failure to call this method results in memory leaks.

Preload the next interstitial ad

Interstitial ads are a one-time-use object. This means once an interstitial ad is shown, the object can't be used again. To request another interstitial ad, create a new InterstitialAd object.

To prepare an interstitial ad for the next impression opportunity, preload the interstitial ad once the OnAdFullScreenContentClosed or OnAdFullScreenContentFailed ad event is raised.

private void RegisterReloadHandler(InterstitialAd interstitialAd)
{
    // Raised when the ad closed full screen content.
    interstitialAd.OnAdFullScreenContentClosed += ()
    {
        Debug.Log("Interstitial Ad full screen content closed.");

        // Reload the ad so that we can show another as soon as possible.
        LoadInterstitialAd();
    };
    // Raised when the ad failed to open full screen content.
    interstitialAd.OnAdFullScreenContentFailed += (AdError error) =>
    {
        Debug.LogError("Interstitial ad failed to open full screen content " +
                       "with error : " + error);

        // Reload the ad so that we can show another as soon as possible.
        LoadInterstitialAd();
    };
}

Best practices

Determine whether interstitial ads are the right type of ad for your app.

Interstitial ads work best in apps with natural transition points. The conclusion of a task within an app, such as sharing an image or completing a game level, creates such a point. Make sure you consider at which points in your app's flow to best display interstitial ads and how the user is likely to respond.

Pause the action when displaying an interstitial ad.

There are a number of different types of interstitial ads such as text, image, or video. It's important to make sure that when your app displays an interstitial ad, it also suspends its use of some resources to allow the ad to take advantage of them. For example, when you make the call to display an interstitial ad, be sure to pause any audio output being produced by your app. You can resume playing sounds in the OnAdFullScreenContentClosed() event, which can be invoked when the user has finished interacting with the ad. In addition, consider temporarily halting any intense computation tasks, such as a game loop, while the ad is being displayed. This ensures that the user doesn't experience slow or unresponsive graphics or stuttered video.

Don't flood the user with ads.

While increasing the frequency of interstitial ads in your app might seem like a great way to increase revenue, it can also degrade the user experience and lower click-through rates. Make sure that users aren't so frequently interrupted that they're no longer able to enjoy the use of your app.

Additional resources

• HelloWorld example: A minimal implementation of all ad formats.