Quảng cáo khi mở ứng dụng

import 'package:google_mobile_ads/google_mobile_ads.dart';
import 'dart:io' show Platform;

class AppOpenAdManager {
  
  String adUnitId = '/21775744923/example/app-open';
  
  AppOpenAd? _appOpenAd;
  bool _isShowingAd = false;

  /// Load an AppOpenAd.
  void loadAd() {
    // We will implement this below.
  }

  /// Whether an ad is available to be shown.
  bool get isAdAvailable {
    return _appOpenAd != null;
  }
}

public class AppOpenAdManager {
  ...

  /// Load an AppOpenAd.
  void loadAd() {
    AppOpenAd.loadWithAdManagerAdRequest(
      adUnitId: adUnitId,
      adManagerAdRequest: AdManagerAdRequest(),
      adLoadCallback: AppOpenAdLoadCallback(
        onAdLoaded: (ad) {
          _appOpenAd = ad;
        },
        onAdFailedToLoad: (error) {
          print('AppOpenAd failed to load: $error');
          // Handle the error.
        },
      ),
    );
  }
}

public class AppOpenAdManager {
  ...

  public void showAdIfAvailable() {
    if (!isAdAvailable) {
      print('Tried to show ad before available.');
      loadAd();
      return;
    }
    if (_isShowingAd) {
      print('Tried to show ad while already showing an ad.');
      return;
    }
    // Set the fullScreenContentCallback and show the ad.
    _appOpenAd!.fullScreenContentCallback = FullScreenContentCallback(
      onAdShowedFullScreenContent: (ad) {
        _isShowingAd = true;
        print('$ad onAdShowedFullScreenContent');
      },
      onAdFailedToShowFullScreenContent: (ad, error) {
        print('$ad onAdFailedToShowFullScreenContent: $error');
        _isShowingAd = false;
        ad.dispose();
        _appOpenAd = null;
      },
      onAdDismissedFullScreenContent: (ad) {
        print('$ad onAdDismissedFullScreenContent');
        _isShowingAd = false;
        ad.dispose();
        _appOpenAd = null;
        loadAd();
      },
    );
  }
}

import 'package:app_open_example/app_open_ad_manager.dart';
import 'package:google_mobile_ads/google_mobile_ads.dart';

/// Listens for app foreground events and shows app open ads.
class AppLifecycleReactor {
  final AppOpenAdManager appOpenAdManager;

  AppLifecycleReactor({required this.appOpenAdManager});

  void listenToAppStateChanges() {
    AppStateEventNotifier.startListening();
    AppStateEventNotifier.appStateStream
        .forEach((state) => _onAppStateChanged(state));
  }

  void _onAppStateChanged(AppState appState) {
    // Try to show an app open ad if the app is being resumed and
    // we're not already showing an app open ad.
    if (appState == AppState.foreground) {
      appOpenAdManager.showAdIfAvailable();
    }
  }
}

import 'package:app_open_example/app_open_ad_manager.dart';
import 'package:flutter/material.dart';
import 'package:google_mobile_ads/google_mobile_ads.dart';

import 'app_lifecycle_reactor.dart';

void main() {
  WidgetsFlutterBinding.ensureInitialized();
  MobileAds.instance.initialize();
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'App Open Example',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'App Open Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

/// Example home page for an app open ad.
class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;
  late AppLifecycleReactor _appLifecycleReactor;

  @override
  void initState() {
    super.initState();
    
    AppOpenAdManager appOpenAdManager = AppOpenAdManager()..loadAd();
    _appLifecycleReactor = AppLifecycleReactor(
      appOpenAdManager: appOpenAdManager);
  }