How to add adaptive banner ads in my flutter app using google mobile ads?

Question

I am using google_mobile_ads with flutter. I want to know how to add adaptive banner ads. this is my code.

@override
      Widget build(BuildContext context) {
        TargetPlatform os = Theme.of(context).platform;
        BannerAd banner = BannerAd(
          listener: BannerAdListener(
            onAdFailedToLoad: (Ad ad, LoadAdError error) {},
            onAdLoaded: (_) {},
          ),
          size: AdSize.banner,
          adUnitId: UNIT_ID[os == TargetPlatform.iOS ? 'ios' : 'android']!,
          request: AdRequest(),
        )..load();



return Scaffold(
appBar: AppBar(…),
body:SafeArea(
　child: Column(
　　children:[
　　　SizedBox(…),　
　　　SizedBox(
　　　　child:AdWidget(
　　　　　ad:banner)
　　　　　),))]

Answer 1

Try this:

class HomeScreen extends StatefulWidget {
  const HomeScreen({Key? key}) : super(key: key);

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

class _BodyState extends State< HomeScreen > {
  BannerAd? _bannerAd = BannerAd(
      adUnitId: Platform.isAndroid 
        ? 'ca-app-pub-3940256099942544/6300978111' 
        : 'ca-app-pub-3940256099942544/2934735716',
      size: AdSize.banner,
      request: AdRequest(),
      listener: BannerAdListener(),
    );
 

  @override
  void initState() {
    super.initState();
    _bannerAd?.load();
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Container(
          alignment: Alignment.center,
          child: AdWidget(ad: _bannerAd!);,
          width: size.width,
          height: 70,
        ),

      ],
    );
  }
}