I get an IllegalStateException sometimes in flutter app after adding native ads to a listview - flutter

Question

this is the error I get:
setState() called after dispose(): _PlatformViewLinkState#bc2a5(lifecycle state: defunct, not mounted)
This error happens if you...
E/flutter ( 4758): [ERROR:flutter/shell/platform/android/platform_view_android_jni_impl.cc(49)] java.lang.IllegalStateException: PlatformView#getView() returned null, but an Android view reference was expected.
I'm using the google_mobile_ads package and not the firebase_ads one since it's deprecated.
I'm trying to put native ads in a list of cards, after a fixed number of elements in the listview.
The way I did this is by using a provider in the main.dart file:
...
void main() {
WidgetsFlutterBinding.ensureInitialized();
final initFuture = MobileAds.instance.initialize();
final adState = AdState(initFuture);
runApp(Provider.value(
value: adState,
builder: (context, child) => MyApp(),
));
}
...
the screen containing the listview is called chapters_screen.dart, when going to this screen the app sometimes crashes. In this file there is a list of items List<Object> itemList = []; as a state variable. In init state the list is populated with offline data as so: itemList = List.from(chaptersData);,
this is how I add the ads in the list:
#override
void didChangeDependencies() {
super.didChangeDependencies();
final adState = Provider.of<AdState>(context);
if(this.mounted){
adState.initialization.then((status) {
if(this.mounted){
setState(() {
for (int i = itemList.length - 2; i >= 1; i -= 2) {
itemList.insert(
i,
// BannerAd(
// adUnitId: adState.bannerAdUnitId,
// size: AdSize.banner,
// request: AdRequest(),
// listener: adState.adListener,
// )..load(),
NativeAd(
adUnitId: adState.nativeAdUnitId,
factoryId: 'listTile',
request: AdRequest(),
listener: NativeAdListener(
onAdLoaded: (_) {
print('ad is loaded succesfully!');
},
onAdFailedToLoad: (ad, error) {
// Releases an ad resource when it fails to load
ad.dispose();
print('Ad load failed (code=${error.code} message=${error.message})'); },
),
)..load(),
);
}
});
}
});
}
}
I tried it before with a banner ad and there is no problem. I followed this tutorial: https://www.youtube.com/watch?v=m0d_pbgeeG8 but I had to change the google_mobile_ads package version to a newer one to be able to use the same NativeAdFactory as in the flutter documentation. The problem is in the newer version the AdListener object no longer exists so instead of passing: listener: adState.adListener like in the video. I put the listener as the code above in the 'NativeAd()' widget.
this is how I'm checking for the type of the listItem to build it in the listView:
Widget _buildListView(BuildContext context) {
List<Widget> widgetList = [];
for (int i = 0; i < itemList.length; i++) {
if (itemList[i] is NativeAd) {
widgetList.add(Container(
height: 200,
child: AdWidget(ad: itemList[i] as NativeAd),
color: Colors.black));
} else {
widgetList.add(ChapterCard(chapter: Chapter.fromJson(itemList[i])));
}
}
return Container(
decoration: BoxDecoration(
image: DecorationImage(
image: AssetImage("assets/images/blured_background.jpg"),
fit: BoxFit.cover,
),
),
child: ListView(children: widgetList.toList()),
);
}
I think I'm doing something wrong in the provider or in the factory class but I'm not sure.
the factory class for android (in java):
import com.google.android.gms.ads.nativead.NativeAd;
import com.google.android.gms.ads.nativead.NativeAdView;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.Map;
import io.flutter.plugins.googlemobileads.GoogleMobileAdsPlugin;
class ListTileNativeAdFactory implements GoogleMobileAdsPlugin.NativeAdFactory {
private final Context context;
ListTileNativeAdFactory(Context context) {
this.context = context;
}
#Override
public NativeAdView createNativeAd(
NativeAd nativeAd, Map<String, Object> customOptions) {
NativeAdView nativeAdView = (NativeAdView) LayoutInflater.from(context)
.inflate(R.layout.list_tile_native_ad, null);
TextView attributionViewSmall = nativeAdView
.findViewById(R.id.tv_list_tile_native_ad_attribution_small);
TextView attributionViewLarge = nativeAdView
.findViewById(R.id.tv_list_tile_native_ad_attribution_large);
ImageView iconView = nativeAdView.findViewById(R.id.iv_list_tile_native_ad_icon);
NativeAd.Image icon = nativeAd.getIcon();
if (icon != null) {
attributionViewSmall.setVisibility(View.VISIBLE);
attributionViewLarge.setVisibility(View.INVISIBLE);
iconView.setImageDrawable(icon.getDrawable());
} else {
attributionViewSmall.setVisibility(View.INVISIBLE);
attributionViewLarge.setVisibility(View.VISIBLE);
}
nativeAdView.setIconView(iconView);
TextView headlineView = nativeAdView.findViewById(R.id.tv_list_tile_native_ad_headline);
headlineView.setText(nativeAd.getHeadline());
nativeAdView.setHeadlineView(headlineView);
TextView bodyView = nativeAdView.findViewById(R.id.tv_list_tile_native_ad_body);
bodyView.setText(nativeAd.getBody());
bodyView.setVisibility(nativeAd.getBody() != null ? View.VISIBLE : View.INVISIBLE);
nativeAdView.setBodyView(bodyView);
nativeAdView.setNativeAd(nativeAd);
return nativeAdView;
}
}
The MainActivity class:
import androidx.annotation.NonNull;
import io.flutter.embedding.android.FlutterActivity;
import io.flutter.embedding.engine.FlutterEngine;
import io.flutter.plugins.googlemobileads.GoogleMobileAdsPlugin;
public class MainActivity extends FlutterActivity {
#Override
public void configureFlutterEngine(#NonNull FlutterEngine flutterEngine) {
super.configureFlutterEngine(flutterEngine);
// TODO: Register the ListTileNativeAdFactory
GoogleMobileAdsPlugin.registerNativeAdFactory(flutterEngine, "listTile",
new ListTileNativeAdFactory(getContext()));
}
#Override
public void cleanUpFlutterEngine(#NonNull FlutterEngine flutterEngine) {
super.cleanUpFlutterEngine(flutterEngine);
// TODO: Unregister the ListTileNativeAdFactory
GoogleMobileAdsPlugin.unregisterNativeAdFactory(flutterEngine, "listTile");
}
}