How to 'await' ads load call back?

Question

I want to load the ad first and showAd() later. Although I use await on load, it still does not 'await' in InterstitialAdLoadCallback() since it is a callback.

InterstitialAd? _interstitialAd;
print("OUTPUT 1");
await InterstitialAd.load(
  adUnitId: '123456789',
  request: AdRequest(),
  adLoadCallback: InterstitialAdLoadCallback(
    onAdLoaded: (ad) {
      print("OUTPUT 2");
      _interstitialAd = ad;
    },
    onAdFailedToLoad: (err) {
      _interstitialAd = null;
    },
  ),
);
print("OUTPUT 3");

Output:

OUTPUT 1
OUTPUT 3
OUTPUT 2

How to 'await' in InterstitialAdLoadCallback()?

Answer 1

If you want to await an operation that does not directly expose a Future, you can use a Completer to create and manage one:

var adCompleter = Completer<void>();
InterstitialAd? _interstitialAd;
await InterstitialAd.load(
  adUnitId: '123456789',
  request: AdRequest(),
  adLoadCallback: InterstitialAdLoadCallback(
    onAdLoaded: (ad) {
      _interstitialAd = ad;
      adCompleter.complete();
    },
    onAdFailedToLoad: (err) {
      _interstitialAd = null;
      adCompleter.completeError(err);
    },
  ),
);
await adCompleter.future;