Interstitial ads are full-screen ads that appear at transition points in your app, such as between screens or during the pause between levels in a game. Your users can tap the ad to visit the destination, or close the ad and return to the app. For details, see [Interstitial ad guidance](https://support.google.com/admob/answer/6066980) and a [case study](https://admob.google.com/home/resources/freaking-math-powers-revenue-increase-with-google-admob-support/). To eliminate presentation latency and make sure an ad is available when a transition occurs, Google Mobile Ads SDK for React Native uses ad preloading to manage background loading, caching, and buffer replenishment. This guide shows you how to integrate interstitial ads into a React Native app. ## Prerequisites Before you continue, do the following: - [Set up Google Mobile Ads SDK for React Native](https://developers.google.com/admob/react-native/quick-start.md.txt). - [Enable test ads](https://developers.google.com/admob/react-native/test-ads.md.txt) and use the following test ad unit: ### Android ca-app-pub-3940256099942544/1033173712 ### iOS ca-app-pub-3940256099942544/4411468910 ## Understand ad preloading Ad preloading in Google Mobile Ads SDK for React Native automates ad loading and caching. Ad preloading provides the following benefits: - **Reference management**: maintains references until ads are shown. - **Automatic reloading**: loads a new ad when one is retrieved from the cache. - **Managed retries**: loads a new ad when one fails to load. - **Expiration handling**: refreshes ads before expiring. - **Cache optimization**: optimizes the cache order to deliver the highest priority ad. To load ads manually, see the [Load a single interstitial ad](https://developers.google.com/admob/react-native/interstitial/single-load.md.txt) guide. ## Start preloading To start preloading ads, call the [`InterstitialAdPreloader.start`](https://developers.google.com/admob/react-native/reference/class/InterstitialAdPreloader#InterstitialAdPreloader.start) method and pass your `preloadId` value, configuration settings, and event callbacks to monitor buffer state changes: ```tsx export function startPreloader( adUnitId: string, preloadId: string, customPreloadCallback?: PreloadCallback, ): boolean { try { const started = InterstitialAdPreloader.start( preloadId, { request: {adUnitId}, bufferSize: 2, }, { // Called when an ad is preloaded into the buffer. onAdPreloaded: (metadata) => { console.log(`Interstitial ad preloaded for ${metadata.preloadId}`); customPreloadCallback?.onAdPreloaded?.(metadata); }, // Called when an ad fails to preload. onAdFailedToPreload: (error: LoadAdError) => { console.error('Failed to preload interstitial ad:', error.message); customPreloadCallback?.onAdFailedToPreload?.(error); }, // Called when all preloaded ads in the buffer have been shown. onAdsExhausted: () => { console.log('Preload buffer exhausted for interstitial ads.'); customPreloadCallback?.onAdsExhausted?.(); }, }, ); return started; } catch (error) { console.error('Error starting interstitial ad preloader:', error); return false; } } ``` A preload ID is a string that uniquely identifies an ad preloading configuration. If you use the ad unit ID for a single preloading configuration in your app, use that ad unit ID as the preload ID. If your app requires multiple preloaders for the same ad unit ID, pass distinct strings for each preload ID. When your app polls a preloaded ad from the buffer, Google Mobile Ads SDK for React Native requests a replacement ad in the background to refill the buffer. If no preloaded ads remain in the buffer, Google Mobile Ads SDK for React Native invokes the [`onAdsExhausted`](https://developers.google.com/admob/react-native/reference/interface/PreloadCallback.md.txt#PreloadCallback.onAdsExhausted) callback. ### Preload cache limits Google Mobile Ads SDK for React Native enforces an app-wide limit on the total number of preloaded ads across all ad units and preload IDs: - Default limit: Google holds a maximum of six preloaded ads in memory. This limit is shared across all formats and preload IDs. - Recommended buffer: Two preloaded ads for each preload ID. If your app reaches the app-wide limit, background requests for preloaded ads pause until existing ads are polled from the cache or destroyed. Preloading also temporarily pauses while a full-screen ad is actively displayed on screen. ## Poll and show the ad Before showing an ad, verify an ad is available by calling the [`InterstitialAdPreloader.isAdAvailable`](https://developers.google.com/admob/react-native/reference/class/InterstitialAd.md.txt#InterstitialAd.isAdAvailable) method. To retrieve the ad, call the [`InterstitialAdPreloader.pollAd`](https://developers.google.com/admob/react-native/reference/class/InterstitialAdPreloader#InterstitialAdPreloader.pollAd) method. To listen for presentation events, like ad dismissals or display failures, set the [`adEventCallback`](https://developers.google.com/admob/react-native/reference/class/InterstitialAd.md.txt#InterstitialAd.adEventCallback) property on the ad instance before calling the [`show`](https://developers.google.com/admob/react-native/reference/class/InterstitialAd.md.txt#InterstitialAd.show) method. The following example checks for ad availability, and listens for full-screen presentation events before showing the ad: ```tsx export function showPreloadedAd( preloadId: string, customAdEventCallback?: FullScreenAdEventCallback, ) { if (InterstitialAdPreloader.isAdAvailable(preloadId)) { const ad = InterstitialAdPreloader.pollAd(preloadId); if (ad) { ad.adEventCallback = { // Called when the ad is presented on screen. onAdShowedFullScreenContent: () => { console.log('Preloaded interstitial ad showed full screen content.'); customAdEventCallback?.onAdShowedFullScreenContent?.(); }, // Called when the ad is closed by the user. onAdDismissedFullScreenContent: () => { console.log('Preloaded interstitial ad dismissed.'); customAdEventCallback?.onAdDismissedFullScreenContent?.(); ad.destroy(); }, // Called when presentation fails. onAdFailedToShowFullScreenContent: (error) => { console.error('Preloaded interstitial ad failed to show:', error); customAdEventCallback?.onAdFailedToShowFullScreenContent?.(error); ad.destroy(); }, // Called when an impression is recorded. onAdImpression: () => { console.log('Preloaded interstitial ad recorded an impression.'); customAdEventCallback?.onAdImpression?.(); }, // Called when the user taps the ad. onAdClicked: () => { console.log('Preloaded interstitial ad was clicked.'); customAdEventCallback?.onAdClicked?.(); }, // Called when the ad is estimated to have earned money. onAdPaid: (adValue) => { console.log( `Preloaded interstitial ad paid: ${adValue.amountMicros}` + ` ${adValue.currencyCode}`, ); customAdEventCallback?.onAdPaid?.(adValue); }, }; ad.show(); } } else { console.log('No preloaded interstitial ad available in buffer.'); } } ``` To release memory and resources, call the `ad.destroy` method in the [`onAdDismissedFullScreenContent`](https://developers.google.com/admob/react-native/reference/interface/FullScreenAdEventCallback#FullScreenAdEventCallback.onAdDismissedFullScreenContent) and [`onAdFailedToShowFullScreenContent`](https://developers.google.com/admob/react-native/reference/interface/FullScreenAdEventCallback#FullScreenAdEventCallback.onAdFailedToShowFullScreenContent) callbacks. ## Read the response info To inspect response info for the next preloaded ad without removing the ad from the cache, call the [`InterstitialAdPreloader.peekAdResponseInfo`](https://developers.google.com/admob/react-native/reference/class/InterstitialAdPreloader#InterstitialAdPreloader.peekAdResponseInfo) method: ```tsx export function peekPreloadedAdResponseInfo(preloadId: string) { if (InterstitialAdPreloader.isAdAvailable(preloadId)) { const responseInfo = InterstitialAdPreloader.peekAdResponseInfo(preloadId); if (responseInfo) { console.log('Next preloaded ad response info:', responseInfo); } } } ``` If an ad is available, the `peekAdResponseInfo` method returns a [`ResponseInfo`](https://developers.google.com/admob/react-native/reference/interface/ResponseInfo.md.txt) object containing information about the loaded ad source and network adapters. ## Clean up resources If you no longer need to show ads for a specific preload ID for the rest of the session, call the [`InterstitialAdPreloader.destroy`](https://developers.google.com/admob/react-native/reference/class/InterstitialAdPreloader#InterstitialAdPreloader.destroy) method. This process stops preloading for that preload ID and frees unused preloaded ads from memory. The following example stops preloading: ```tsx export function destroyPreloader(preloadId: string) { InterstitialAdPreloader.destroy(preloadId); } ``` After your user dismisses the ad or the ad fails to show, destroy individual polled ad instances. For details, see [Poll and show the ad](https://developers.google.com/admob/react-native/interstitial.md.txt#poll_and_show). ## View the full example The following example component starts preloading on mount, tracks available ad counts, and provides controls to show preloaded interstitial ads: ```tsx export function InterstitialScreen() { const [numAdsAvailable, setNumAdsAvailable] = useState(0); const [status, setStatus] = useState('Initializing Preloader...'); const refreshAdCount = () => { const count = InterstitialAdPreloader.getNumAdsAvailable(PRELOAD_ID); setNumAdsAvailable(count); }; useEffect(() => { // Start preloading interstitial ads on component mount startPreloader(INTERSTITIAL_AD_UNIT_ID, PRELOAD_ID, { onAdPreloaded: () => { refreshAdCount(); setStatus('Ad preloaded and ready!'); }, onAdFailedToPreload: (error) => { setStatus(`Preload failed: ${error.message}`); }, onAdsExhausted: () => { refreshAdCount(); setStatus('Preload buffer exhausted.'); }, }); setStatus('Preloader started.'); // Clean up preloader resources on component unmount return () => { destroyPreloader(PRELOAD_ID); }; }, []); const handleShow = () => { showPreloadedAd(PRELOAD_ID, { onAdDismissedFullScreenContent: () => { setStatus('Ad dismissed.'); }, onAdFailedToShowFullScreenContent: (error) => { setStatus(`Failed to show ad: ${error.message}`); }, }); setStatus('Showing preloaded ad...'); refreshAdCount(); }; return ( Preload Interstitial Ads Status: {status} Ads Available: {numAdsAvailable}