Interstitial ads

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Interstitial ads are full-screen ads that cover the interface of an app until closed by the user. They're typically displayed at natural transition points in the flow of an app, such as between activities or 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 shows you how to integrate interstitial ads into Android and iOS apps using the Google Mobile Ads C++ SDK.

Prerequisites

Always test with test ads

When building and testing your apps, make sure you use test ads rather than live, production ads. Failure to do so can lead to suspension of your account.

The easiest way to load test ads is to use our dedicated test ad unit ID for interstitials, which varies per device platform:

  • Android: ca-app-pub-3940256099942544/1033173712
  • iOS: ca-app-pub-3940256099942544/4411468910

They've been specially configured to return test ads for every request, and you're free to use it in your own apps while coding, testing, and debugging. Just make sure you replace it with your own ad unit ID before publishing your app.

For more information about how the Mobile Ads SDK's test ads work, see Test Ads.

Implementation

The main steps to integrate interstitial ads are:

  1. Load an ad.
  2. Register for callbacks.
  3. Display the ad and handle its lifecycle events.

Configure an InterstitialAd

Interstitial ads are displayed in InterstitialAd objects, so the first step toward integrating interstitial ads into your app is to create and initialize an InterstitialAd object.

  1. Add the following header to your app's C++ code:

     #include "firebase/gma/interstial_ad.h"
    

  2. Declare and instantiate an InterstitialAd object:

     firebase::gma::InterstitialAd* interstitial_ad;
     interstitial_ad = new firebase::gma::InterstitialAd();
    

  3. Initialize the InterstitialAd instance using your parent view cast to an AdParent type. The parent view is a JNI jobject reference to an Android Activity or a pointer to an iOS UIView.

    // my_ad_parent is a jobject reference to an Android Activity or
    // a pointer to an iOS UIView.
    firebase::gma::AdParent ad_parent =
      static_cast<firebase::gma::AdParent>(my_ad_parent);
    firebase::Future<void> result = interstitial_ad->Initialize(ad_parent);
    
  4. As an alternative to retaining the future as a variable, you can periodically check the status of the initialization operation by invoking InitializeLastResult() on the InterstitialAd object. This may be helpful for keeping track of the initialization process in your global game loop.

    // Monitor the status of the future in your game loop:
    firebase::Future<void> result = interstitial_ad->InitializeLastResult();
    if (result.status() == firebase::kFutureStatusComplete) {
      // Initialization completed.
      if(future.error() == firebase::gma::kAdErrorCodeNone) {
        // Initialization successful.
      } else {
        // An error has occurred.
      }
    } else {
      // Initialization on-going.
    }
    

For more information about working with firebase::Future, see Use Futures to monitor the completion status of method calls.

Load an ad

Loading an ad is accomplished using the LoadAd() method on the InterstitialAd object. The load method requires that you've initialized the InterstitialAd object, and that you have your ad unit ID and an AdRequest object. A firebase::Future is returned which you can use to monitor the state and result of the load operation.

The following code shows how to load an ad once the InterstitialAd has been successfully initialized:

firebase::gma::AdRequest ad_request;
firebase::Future<firebase::gma::AdResult> load_ad_result;
load_ad_result = interstitial_ad->LoadAd(interstitial_ad_unit_id, ad_request);

Register for callbacks

You must extend the FullScreenContentListener class in order to receive notifications of interstitial ad presentation and lifecycle events. Your custom FullScreenContentListener subclass can be registered through the InterstitialAd::SetFullScreenContentListener() method, and it will receive callbacks when the ad presents successfully or unsuccessfully as well as when it's dismissed.

The following code shows how to extend the class and assign it to the ad:

  class ExampleFullScreenContentListener
      : public firebase::gma::FullScreenContentListener {

   public:
    ExampleFullScreenContentListener() {}

    void OnAdClicked() override {
      // This method is invoked when the user clicks the ad.
    }

    void OnAdDismissedFullScreenContent() override {
     // This method is invoked when the ad dismisses full screen content.
    }

    void OnAdFailedToShowFullScreenContent(const AdError& error) override {
      // This method is invoked when the ad failed to show full screen content.
      // Details about the error are contained within the AdError parameter.
    }

    void OnAdImpression() override {
      // This method is invoked when an impression is recorded for an ad.
    }

    void OnAdShowedFullScreenContent() override {
      // This method is invoked when the ad showed its full screen content.
    }
  };

  ExampleFullScreenContentListener* full_screen_content_listener =
    new ExampleFullScreenContentListener();
  interstitial_ad->SetFullScreenContentListener(full_screen_content_listener);

InterstitialAd is a one-time-use object. This means that once an interstitial ad is shown, it cannot be shown again. A best practice is to load another interstitial ad in the OnAdDismissedFullScreenContent() method of your FullScreenContentListener so that the next interstitial ad starts loading as soon as the previous one is dismissed.

Display the ad

Interstitials should be displayed during natural pauses in the flow of an app. Between levels of a game is a good example, or after the user completes a task. While the FullScreenContentListener can be used to determine when an ad has shown its full screen content, the future returned by Show() will also signal when the ad has been successfully shown.

  firebase::Future<void> result = interstitial_ad->Show();

Best practices

Consider 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, like sharing an image or completing a game level, creates such a point. Because the user is expecting a break in the action, it's easy to present an interstitial ad without disrupting their experience. Make sure you consider at which points in your app's workflow you'll display interstitial ads and how the user is likely to respond.
Remember to pause the action when displaying an interstitial ad.
There are a number of different types of interstitial ads: text, image, video, and more. 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 OnAdDismissedFullScreenContent method of your installed FullScreenContentListener which will 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 will ensure that the user doesn't experience slow or unresponsive graphics or stuttered video.
Allow for adequate loading time.
Just as it's important to make sure you display interstitial ads at an appropriate time, it's also important to make sure the user doesn't have to wait for them to load. Loading the ad in advance before you intend to show can ensure that your app has a fully loaded interstitial ad at the ready when the time comes to display one.
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 clickthrough rates. Make sure that users aren't so frequently interrupted that they're no longer able to enjoy the use of your app.
Don't use the load completion future to show the interstitial.
This can cause a poor user experience. Instead, pre-load the ad before you need to show it.

Additional resources

Example in GitHub

Mobile Ads Garage video tutorials

Success stories

Next steps