#Lecture 002 — The AdmobManager: Test vs Real Ids

Every ad format needs an ad unit id. Scattering them through the code is how real ids reach a debug build by accident. We keep all ids in one class that automatically hands out test ids while you debug.

Contents

Prerequisites · Connection · Objectives · Lesson · Code Examples · Common Mistakes · Best Practices · Mini Challenge · Practice Questions · Answers · Takeaways

#Prerequisites

Lecture 001: plugin and app ids in place. Dart static, Map, and kDebugMode.

#Connection With Previous Lectures

Lecture 001 added the app id (one per app). Now we add the ad unit ids (one per placement and format) in code.

#Learning Objectives

By the end of this lecture you will be able to:

• Explain app id vs ad unit id
• Write an AdmobManager with test, Android and iOS id maps
• Switch ids by platform and by debug/release
• Keep real ids out of debug builds

#Lesson

#1. App Id vs Ad Unit Id

• App id (ca-app-pub-…~…, with a tilde) — identifies the whole app. It lives in the manifest and Info.plist.
• Ad unit id (ca-app-pub-…/…, with a slash) — identifies one placement, such as "the banner on the home screen". It lives in Dart.

#2. The Manager

All ids sit in one file. Debug builds return Google's test ids; release builds return your real ids for the platform the app is running on.

// lib/admob/admob_manager.dart
import 'dart:io';

import 'package:flutter/foundation.dart';

class AdmobManager {
  /// In debug builds, show Google's test ads. Never ship real ids while testing.
  static const bool showTestAdsInDebug = true;

  static const _testIds = {
    'bannerAdaptive': 'ca-app-pub-3940256099942544/9214589741',
    'bannerFixed': 'ca-app-pub-3940256099942544/6300978111',
    'interstitial': 'ca-app-pub-3940256099942544/1033173712',
    'rewardedInterstitial': 'ca-app-pub-3940256099942544/5354046379',
    'rewarded': 'ca-app-pub-3940256099942544/5224354917',
    'native': 'ca-app-pub-3940256099942544/2247696110',
    'appOpen': 'ca-app-pub-3940256099942544/9257395921',
  };

  // Your real ids from the AdMob dashboard (Apps → Ad units).
  static const _androidIds = {
    'bannerAdaptive': '',
    'bannerFixed': '',
    'interstitial': '',
    'rewardedInterstitial': '',
    'rewarded': '',
    'native': '',
    'appOpen': '',
  };

  static const _iosIds = {
    'bannerAdaptive': '',
    'bannerFixed': '',
    'interstitial': '',
    'rewardedInterstitial': '',
    'rewarded': '',
    'native': '',
    'appOpen': '',
  };

  static Map<String, String> get _ids {
    if (kDebugMode && showTestAdsInDebug) return _testIds;
    return Platform.isAndroid ? _androidIds : _iosIds;
  }

  static String get bannerAdaptiveId => _ids['bannerAdaptive'] ?? '';
  static String get bannerFixedId => _ids['bannerFixed'] ?? '';
  static String get interstitialId => _ids['interstitial'] ?? '';
  static String get rewardedInterstitialId =>
      _ids['rewardedInterstitial'] ?? '';
  static String get rewardedId => _ids['rewarded'] ?? '';
  static String get nativeId => _ids['native'] ?? '';
  static String get appOpenId => _ids['appOpen'] ?? '';
}

• kDebugMode — true only when running in debug.
• showTestAdsInDebug — a switch to turn real ads on in debug later (for a final check).
• The real-id maps are empty now. You fill them in Lecture 010 from the AdMob dashboard.
• Each getter (bannerAdaptiveId, …) hides the map keys, so the rest of the app writes AdmobManager.interstitialId and never a raw string.

#3. Why Not Hard-Code Ids?

A hard-coded real id in a debug build means your own testing taps produce invalid traffic. One class with a debug switch makes that mistake impossible.

#Code Examples

#Example 1 — Using an Id

adUnitId: AdmobManager.interstitialId,

In debug this is ca-app-pub-3940256099942544/1033173712, Google's sample interstitial.

#Common Beginner Mistakes

1. An empty id in release — ads fail to load with an invalid ad unit error. Fill every id before release.

2. Android id in the iOS map — ads do not load on iOS.

3. Real id + debug — only if you set showTestAdsInDebug = false on purpose.

#Best Practices

• One id per placement and format
• Keep ids in one file; never in widgets
• Create separate ad units for separate screens so reports show what earns

#Mini Challenge

Add an 'appOpen' entry check: print AdmobManager.appOpenId from main in debug and confirm it is Google's sample id.

#Practice Questions

1. What is the difference in format between an app id and an ad unit id?
2. What does kDebugMode do here?
3. Why are there two real-id maps?
4. Where do real ids come from?

#Practice Answers

1. App id has ~, ad unit id has /.
2. Makes debug builds return test ids.
3. Android and iOS have different ad unit ids.
4. The AdMob dashboard, under Apps → Ad units.

#Key Takeaways

• App id in platform files, ad unit ids in AdmobManager
• Debug = test ids, release = real ids
• Fill the real maps before release