Hey there! I’ve tackled this exact scenario before with the google_mobile_ads plugin, so let me walk you through how to pull off showing different native ads at specific positions in your ListView.

Core Idea #

The key is to merge your regular content items and ad entries into a single data list, then render each item based on its type. This lets you insert distinct native ads (with different ad unit IDs or layouts) wherever you need them.

Step 1: Define a Unified List Item Model #

First, create a model to distinguish between regular content and different ad types. This helps the ListView know what to render for each entry:

enum ListItemType { content, nativeAdPromo, nativeAdSponsored }

class ListItem {
  final ListItemType type;
  final dynamic data; // Holds content text or ad unit ID

  ListItem(this.type, this.data);
}

Step 2: Build Your Combined Data Source #

Generate a list that mixes your regular content with the ad positions you want. For example, insert a "promo" ad at index 2 and a "sponsored" ad at index 7:

List<ListItem> buildMixedList() {
  final items = <ListItem>[];
  
  // Add 10 regular content items
  for (int i = 0; i < 10; i++) {
    items.add(ListItem(ListItemType.content, "Regular Content Item $i"));
  }
  
  // Insert different ads at specific positions
  items.insert(2, ListItem(ListItemType.nativeAdPromo, "ca-app-pub-XXX/XXX"));
  items.insert(7, ListItem(ListItemType.nativeAdSponsored, "ca-app-pub-YYY/YYY"));
  
  return items;
}

Step 3: Handle Ad Loading & Caching #

Create a way to load and cache native ads by their ad unit ID. This prevents redundant loads and keeps track of which ads are ready:

final Map<String, NativeAd?> _loadedAds = {};

void _loadAd(String adUnitId) {
  if (_loadedAds.containsKey(adUnitId)) return;

  final nativeAd = NativeAd(
    adUnitId: adUnitId,
    factoryId: adUnitId.contains("XXX") ? "promo_ad_factory" : "sponsored_ad_factory",
    request: const AdRequest(),
    listener: NativeAdListener(
      onAdLoaded: (ad) => setState(() => _loadedAds[adUnitId] = ad as NativeAd),
      onAdFailedToLoad: (ad, error) {
        ad.dispose();
        _loadedAds.remove(adUnitId);
        print("Ad failed to load: $error");
      },
    ),
  );

  nativeAd.load();
}

Note: Use different factoryId values if you want distinct layouts for each ad type (you'll need to configure these in your Android/iOS project).

Step 4: Render the ListView #

In your build method, map each list item to the correct widget. Show loading states while ads are loading, and the ad once it's ready:

@override
Widget build(BuildContext context) {
  final mixedList = buildMixedList();
  
  // Preload ads when the widget initializes
  for (final item in mixedList) {
    if (item.type == ListItemType.nativeAdPromo || item.type == ListItemType.nativeAdSponsored) {
      _loadAd(item.data as String);
    }
  }

  return ListView.builder(
    itemCount: mixedList.length,
    itemBuilder: (context, index) {
      final item = mixedList[index];
      
      switch (item.type) {
        case ListItemType.content:
          return ListTile(title: Text(item.data as String));
        
        case ListItemType.nativeAdPromo:
        case ListItemType.nativeAdSponsored:
          final ad = _loadedAds[item.data as String];
          if (ad == null) {
            return const SizedBox(
              height: 120,
              child: Center(child: CircularProgressIndicator()),
            );
          }
          return Padding(
            padding: const EdgeInsets.symmetric(vertical: 8, horizontal: 16),
            child: NativeAdWidget(ad: ad),
          );
      }
    },
  );
}

Step 5: Clean Up Resources #

Don't forget to dispose of loaded ads when the widget is destroyed to avoid memory leaks:

@override
void dispose() {
  for (final ad in _loadedAds.values) {
    ad?.dispose();
  }
  super.dispose();
}

Pro Tips #

• Lazy Loading: Instead of preloading all ads upfront, use a ScrollController or VisibilityDetector to load ads only when they're about to enter the viewport. This saves bandwidth and improves performance.
• Error Handling: Replace loading indicators with a placeholder widget or skip the ad position entirely if an ad fails to load.
• Custom Layouts: Use different factoryId values to style each ad type uniquely (configure these in your native project files).

内容的提问来源于stack exchange，提问作者Calvin