Mobile Programming (MP)

Mobile Programming

Lecturer: Ali Najimi
Faculty of Computer Engineering
Sharif University of Technology
Fall 2027

AdMob Google Ads In-App Purchase Revenue Adivery Cafe Bazaar

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Table of Contents

  1. Mobile Monetization Overview
  2. Ad Types & Ad Networks
  3. Google AdMob — Setup & Integration
  4. Flutter: google_mobile_ads Package
  5. Banner Ads in Flutter
  6. Interstitial Ads in Flutter
  7. Rewarded Ads in Flutter
  8. Native Ads in Flutter
  9. Android Native: Google Mobile Ads SDK
  10. iOS Native: Google Mobile Ads SDK
  11. Iran Market: Adivery + Cafe Bazaar
  12. Adivery Flutter — Setup
  13. Adivery Banner Ads
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Table of Contents

  1. Adivery Interstitial & Rewarded Ads
  2. Adivery Native Ads
  3. In-App Purchase Overview
  4. Flutter: in_app_purchase Package
  5. Cafe Bazaar In-App Billing for Flutter
  6. Cafe Bazaar Purchase Flow
  7. Cafe Bazaar Security & Verification
  8. Consumable & Non-Consumable Purchases
  9. Android: Google Play Billing Library
  10. iOS: StoreKit 2
  11. Subscription Management
  12. Ad & IAP Best Practices
  13. Summary & Key Takeaways
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Mobile Monetization Overview

How do free apps make money? Here are the main strategies:

Monetization Models:

Model How It Works Revenue Type
Paid Apps User pays once to download One-time
In-App Ads Show ads to users CPM / CPC / CPA
In-App Purchase Sell digital goods/features Per transaction
Subscriptions Recurring payment for content Recurring
Freemium Free base + paid premium Mixed

Industry Trend: Most mobile apps are free. Ads + IAP are the dominant revenue model.

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Ad Types & Ad Networks

Common Ad Formats:

  • Banner Ads: Rectangular ads at top/bottom of screen. Low revenue per view.
  • Interstitial Ads: Full-screen ads between screens. Higher revenue, more intrusive.
  • Rewarded Ads: Users watch a video ad in exchange for a reward. Highest eCPM.
  • Native Ads: Custom-styled ads that match your app's look and feel.

Major Ad Networks:

Network Platform Notes
Google AdMob Android, iOS Google Ads inventory
Adivery Android, Flutter Useful for Iranian apps
Meta Audience Network Android, iOS Facebook's ad network
Unity Ads Android, iOS Game-focused
AppLovin / ironSource Android, iOS Mediation + gaming monetization
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Google AdMob — Setup & Integration

AdMob is Google's mobile ad platform. It's widely used in Flutter apps.

Setup Steps:

  1. Create an AdMob account at admob.google.com.
  2. Register your app and get App IDs.
  3. Create ad units and get Ad Unit IDs.
  4. Configure platform-specific settings:

Android (AndroidManifest.xml)


<manifest>
    <application>
        <meta-data
                android:name="com.google.android.gms.ads.APPLICATION_ID"
                android:value="ca-app-pub-xxxx~xxxxxxxxxx"/>
    </application>
</manifest>

iOS (Info.plist)


<key>GADApplicationIdentifier</key>
<string>ca-app-pub-xxxx~xxxxxxxxxx</string>
<key>NSUserTrackingUsageDescription</key>
<string>This identifier will be used to deliver personalized ads.</string>
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Flutter: google_mobile_ads Package

The official Google package for ads in Flutter.

# pubspec.yaml
dependencies:
  google_mobile_ads: ^5.3.0
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Flutter: google_mobile_ads Package

Initialization:

import 'package:google_mobile_ads/google_mobile_ads.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  await MobileAds.instance.initialize();

  final config = RequestConfiguration(
    testDeviceIds: ['YOUR_TEST_DEVICE_ID'],
  );
  MobileAds.instance.updateRequestConfiguration(config);

  runApp(const MyApp());
}

Important: Always test with test ad unit IDs during development.

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Banner Ads in Flutter

Banner ads are rectangular ads displayed at the top or bottom of the screen.

class BannerAdWidget extends StatefulWidget {
  @override
  State<BannerAdWidget> createState() => _BannerAdWidgetState();
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Banner Ads in Flutter (Widget)

class _BannerAdWidgetState extends State<BannerAdWidget> {
  BannerAd? _bannerAd;
  bool _isLoaded = false;
  @override
  void initState() {
    super.initState();
    _bannerAd = BannerAd(
      adUnitId: 'ca-app-pub-3940256099942544/6300978111',
      size: AdSize.banner,
      request: const AdRequest(),
      listener: BannerAdListener(
        onAdLoaded: (_) => setState(() => _isLoaded = true),
        onAdFailedToLoad: (ad, error) => ad.dispose(),
      ),
    ).load();
  }
  @override
  void dispose() { _bannerAd?.dispose(); super.dispose(); }
  @override
  Widget build(BuildContext context) {
    return _isLoaded && _bannerAd != null
      ? SizedBox(
          height: _bannerAd!.size.height.toDouble(),
          width: _bannerAd!.size.width.toDouble(),
          child: AdWidget(ad: _bannerAd!),
        )
      : const SizedBox.shrink();
  }
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Interstitial Ads in Flutter

Interstitial ads are full-screen ads shown at natural transition points.

class InterstitialAdHelper {
  InterstitialAd? _interstitialAd;
  int _numAttempts = 0;
  void createAd() {
    InterstitialAd.load(
      adUnitId: 'ca-app-pub-3940256099942544/1033173712',
      request: const AdRequest(),
      adLoadCallback: InterstitialAdLoadCallback(
        onAdLoaded: (ad) {
          _interstitialAd = ad;
          _numAttempts = 0;
        },
        onAdFailedToLoad: (error) {
          _numAttempts++;
          _interstitialAd = null;
          if (_numAttempts <= 2) createAd();
        },
      ),
    );
  }
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Interstitial Ads in Flutter (cont.)

  void showAd() {
    if (_interstitialAd == null) return;
    _interstitialAd!.fullScreenContentCallback =
      FullScreenContentCallback(
        onAdDismissedFullScreenContent: (ad) {
          ad.dispose();
          createAd();
        },
        onAdFailedToShowFullScreenContent: (ad, error) {
          ad.dispose();
          createAd();
        },
      );
    _interstitialAd!.show();
    _interstitialAd = null;
  }
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Rewarded Ads in Flutter

Rewarded ads let users earn in-app rewards by watching a video ad.

class RewardedAdHelper {
  RewardedAd? _rewardedAd;

  void loadAd() {
    RewardedAd.load(
      adUnitId: 'ca-app-pub-3940256099942544/5224354917',
      request: const AdRequest(),
      rewardedAdLoadCallback: RewardedAdLoadCallback(
        onAdLoaded: (ad) => _rewardedAd = ad,
        onAdFailedToLoad: (error) => _rewardedAd = null,
      ),
    );
  }
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Rewarded Ads in Flutter (cont.)

  void showAd({required Function(RewardItem) onReward}) {
    if (_rewardedAd == null) return;

    _rewardedAd!.fullScreenContentCallback = FullScreenContentCallback(
      onAdDismissedFullScreenContent: (ad) {
        ad.dispose();
        loadAd();
      },
    );

    _rewardedAd!.show(onUserEarnedReward: (ad, reward) {
      onReward(reward);
    });

    _rewardedAd = null;
  }
}
// Usage
adHelper.showAd(onReward: (reward) {
  player.addCoins(reward.amount.toInt());
});
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Native Ads in Flutter

Native ads match your app's visual design — you control the layout.

final NativeAd _nativeAd = NativeAd(
  adUnitId: 'ca-app-pub-3940256099942544/2247696110',
  request: const AdRequest(),
  factoryId: 'my_native_ad',
  listener: NativeAdListener(
    onAdLoaded: (_) => setState(() => _isLoaded = true),
    onAdFailedToLoad: (ad, error) => ad.dispose(),
  ),
).load();
// Display
if (_isLoaded)
  SizedBox(
    height: 300,
    width: 300,
    child: AdWidget(ad: _nativeAd),
  )

Note: Native ads require platform-specific code to define the ad layout.

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Android Native: Google Mobile Ads SDK

For native Android (Kotlin), integrate Google Mobile Ads SDK directly.

Setup (build.gradle):

dependencies {
  implementation 'com.google.android.gms:play-services-ads:23.6.0'
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Android Native: Google Mobile Ads SDK

Initialize and Load Banner (Kotlin):

class MainActivity : AppCompatActivity() {
  lateinit var adView: AdView

  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    MobileAds.initialize(this) {
      adView = findViewById(R.id.adView)
      adView.adUnitId = "ca-app-pub-3940256099942544/6300978111"
      adView.setAdSize(AdSize.BANNER)
      adView.loadAd(AdRequest.Builder().build())
    }
  }
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Android Native: Google Mobile Ads SDK

Interstitial (Kotlin):

InterstitialAd.load(this,
  "ca-app-pub-3940256099942544/1033173712",
  AdRequest.Builder().build(),
  object : InterstitialAdLoadCallback() {
    override fun onAdLoaded(ad: InterstitialAd) { mAd = ad }
    override fun onAdFailedToLoad(e: LoadAdError) { mAd = null }
  })
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

iOS Native: Google Mobile Ads SDK

For native iOS (Swift), use Google Mobile Ads SDK via CocoaPods or SPM.

Setup (Podfile):

pod 'Google-Mobile-Ads-SDK'
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

iOS Native: Google Mobile Ads SDK

Initialize and Load Banner (Swift):

import GoogleMobileAds

class ViewController: UIViewController {
  var bannerView: GADBannerView!

  override func viewDidLoad() {
    super.viewDidLoad()
    MobileAds.shared.start(completionHandler: nil)

    bannerView = GADBannerView(adSize: GADAdSizeBanner)
    bannerView.adUnitID = "ca-app-pub-3940256099942544/2934735716"
    bannerView.rootViewController = self
    bannerView.load(GADRequest())
    view.addSubview(bannerView)
  }
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

iOS Native: Google Mobile Ads SDK

Interstitial (Swift):

GADInterstitialAd.load(
  withAdUnitID: "ca-app-pub-3940256099942544/4411468910",
  request: GADRequest()
) { ad, error in
  if let error = error { print(error); return }
  self.interstitial = ad
  self.interstitial?.present(fromRootViewController: self)
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Iran Market: Adivery + Cafe Bazaar

For apps targeting Iranian Android users, two local services are commonly relevant:

Adivery

  • Local ad network / ad SDK
  • Flutter package: adivery
  • Supports Android Flutter apps
  • Common formats: banner, interstitial, rewarded, native
  • Uses App ID + Placement IDs

Cafe Bazaar IAB

  • Local Android app store billing
  • Flutter options include flutter_poolakey and cafebazaar_flutter
  • Uses Bazaar product IDs and purchase tokens
  • Important for apps distributed through Cafe Bazaar
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Iran Market: Adivery + Cafe Bazaar

Use AdMob / Google Play for global distribution, and Adivery / Cafe Bazaar when your main distribution channel is
Iran-focused Android.

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Adivery Flutter — Setup

Adivery provides a Flutter plugin for activating ads inside Flutter apps.

# pubspec.yaml
dependencies:
  adivery: ^4.8.8
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Adivery Flutter — Setup

Import and initialize:

import 'package:adivery/adivery.dart';
import 'package:adivery/adivery_ads.dart';

void initAds() {
  AdiveryPlugin.initialize("YOUR_ADIVERY_APP_ID");
  AdiveryPlugin.setLoggingEnabled(true); // development only
}

Core identifiers:

Identifier Meaning
App ID Your Adivery application identifier
Placement ID Identifier for each ad placement
Banner Placement Used inside BannerAd widget
Interstitial / Rewarded Placement Prepared, loaded, checked, then shown
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Adivery Banner Ads

Adivery banners are added as Flutter widgets.

BannerAd(
  "YOUR_BANNER_PLACEMENT_ID",
  BannerAdSize.BANNER,
  onAdLoaded: (ad) {
    print("banner loaded");
  },
  onAdClicked: (ad) {
    print("banner clicked");
  },
  onError: (ad, error) {
    print("banner failed: $error");
  },
)
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Adivery Banner Ads

Common banner sizes:

Size Use Case
BannerAdSize.BANNER Standard bottom/top banner
BannerAdSize.LARGE_BANNER Larger banner area
BannerAdSize.MEDIUM_RECTANGLE Feed/card placement

Best practice: Put banners where they do not cover navigation, forms, or game controls.

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Adivery Interstitial & Rewarded Ads

Interstitial and rewarded ads should be prepared before showing.

void prepareFullScreenAds() {
  AdiveryPlugin.prepareInterstitialAd("INTERSTITIAL_PLACEMENT_ID");
  AdiveryPlugin.prepareRewardedAd("REWARDED_PLACEMENT_ID");

  AdiveryPlugin.addListener(
    onInterstitialLoaded: (placement) {
      print("interstitial loaded");
    },
    onRewardedClosed: (placement, isRewarded) {
      if (isRewarded) {
        // deliver reward here
      }
    },
    onError: (placement, error) {
      print("ad error: $error");
    },
  );
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Adivery Interstitial & Rewarded Ads

Show only when loaded:

Future<void> showPlacement(String placementId) async {
  final isLoaded = await AdiveryPlugin.isLoaded(placementId);
  if (isLoaded) {
    AdiveryPlugin.show(placementId);
  }
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Adivery Native Ads

Native ads let you build the UI yourself using ad assets.

NativeAd? nativeAd;

void loadNative() {
  nativeAd = NativeAd(
    "YOUR_NATIVE_PLACEMENT_ID",
    onAdLoaded: () {
      setState(() {});
    },
  );

  nativeAd!.loadAd();
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Adivery Native Ads

Example rendering idea:

if (nativeAd != null && nativeAd!.isLoaded) {
  return Column(
    children: [
      nativeAd!.image,
      Row(
        children: [
          nativeAd!.icon,
          Text(nativeAd!.headline),
        ],
      ),
      Text(nativeAd!.description),
      ElevatedButton(
        onPressed: nativeAd!.recordClick,
        child: Text(nativeAd!.callToAction),
      ),
    ],
  );
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Adivery Native Ads

Always respect the ad network policy: keep the ad recognizable, do not fake clicks, and call click/impression methods
correctly.

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

In-App Purchase Overview

In-App Purchase (IAP) lets users buy digital goods and services inside your app.

Product Types:

Type Description Example
Consumable Used once, can be repurchased Coins, extra lives
Non-Consumable Bought once, permanent Remove ads, premium unlock
Auto-Renewable Sub Recurring billing Monthly premium, cloud storage
Non-Renewing Sub Fixed period access 1-year membership

Platform Stores:

  • Android: Google Play Billing, Cafe Bazaar Billing, Samsung Galaxy Store, Amazon Appstore
  • iOS: Apple App Store / StoreKit
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

In-App Purchase Overview

Rule: For digital goods, use the billing system required by the store that distributes your app.

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Flutter: in_app_purchase Package

The official Flutter plugin for handling in-app purchases on Google Play and Apple App Store.

# pubspec.yaml
dependencies:
  in_app_purchase: ^3.2.1
  in_app_purchase_storekit: ^0.3.7
  in_app_purchase_android: ^0.3.6
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Flutter: in_app_purchase Package

Initialization and Purchase Stream:

import 'package:in_app_purchase/in_app_purchase.dart';
import 'dart:async';
class IAPManager {
  final InAppPurchase _iap = InAppPurchase.instance;
  late StreamSubscription<List<PurchaseDetails>> _subscription;
  List<ProductDetails> _products = [];
  Future<void> init() async {
    final available = await _iap.isAvailable();
    if (!available) return;
    _subscription = _iap.purchaseStream.listen(_onPurchaseUpdate);

    final response = await _iap.queryProductDetails(
      {'coins_100', 'premium_upgrade', 'monthly_sub'},
    );
    _products = response.productDetails.toList();
  }
  void _onPurchaseUpdate(List<PurchaseDetails> purchases) {
    for (final purchase in purchases) {
      if (purchase.status == PurchaseStatus.purchased) {
        _verifyAndDeliver(purchase);
      }
      if (purchase.pendingCompletePurchase) {
        _iap.completePurchase(purchase);
      }
    }
  }
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Cafe Bazaar In-App Billing for Flutter

Cafe Bazaar billing is Android-only and is used for apps distributed through Cafe Bazaar.

Option A: flutter_poolakey

dependencies:
  flutter_poolakey: ^2.2.0+1.0.0

import 'package:flutter_poolakey/flutter_poolakey.dart';

Also add JitPack in Gradle when required:

allprojects {
  repositories {
    maven { url 'https://jitpack.io' }
  }
}

Option B: cafebazaar_flutter

dependencies:
  cafebazaar_flutter: ^2.0.0

import 'package:cafebazaar_flutter/cafebazaar_flutter.dart';

final bazaar = CafebazaarFlutter.instance;
final inapp = bazaar.inAppPurchase(PUBLIC_KEY);

PUBLIC_KEY is taken from the Cafe Bazaar developer panel.

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Cafe Bazaar Purchase Flow

A typical Cafe Bazaar purchase flow:

  1. Create products in the Cafe Bazaar developer panel.
  2. Get your public/RSA key from the panel.
  3. Initialize the billing plugin.
  4. Start a purchase or subscription flow.
  5. Receive purchase data.
  6. Verify signature, payload, product ID, and order ID.
  7. Deliver content.
  8. Consume the purchase if it is consumable.
  9. Disconnect / dispose billing connection when done.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Cafe Bazaar Purchase Flow

final PurchaseInfo purchaseInfo = await inapp.purchase(
  "productId",
  payLoad: "unique_payload_per_request",
);

if (purchaseInfo != null) {
  // send purchaseInfo to backend for verification
  // then unlock item or add coins
}

Subscription:

final PurchaseInfo purchaseInfo = await inapp.subscribe(
  "subscriptionProductId",
  payLoad: "unique_payload_per_request",
);
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Cafe Bazaar Security & Verification

Never deliver paid content only because the client says “success”.

Important fields to validate:

Field Why It Matters
productId Confirms the purchased item
purchaseToken Used for tracking and consuming purchases
orderId Must be unique; prevents replay attacks
payload / developerPayload Should match the request token you generated
dataSignature Used to verify authenticity
packageName Confirms the purchase belongs to your app

Consumable purchase:

final bool consumeResult = await inapp.consume(
  purchaseInfo.purchaseToken,
);

Security checklist:

  • Generate a unique payload per purchase request.
  • Verify purchase data on your backend.
  • Reject reused orderId or mismatched payload.
  • Keep public/RSA key handling clean and do not hard-code secrets beyond what is required by the SDK.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Consumable and Non-Consumable Purchases

Consumable (coins, lives):

final param = PurchaseParam(productDetails: product);
_iap.buyConsumable(purchaseParam: param);

// On purchase success:
// 1. Verify server-side
// 2. Add coins
// 3. Mark token consumed

Non-Consumable (premium):

final param = PurchaseParam(productDetails: product);
_iap.buyNonConsumable(purchaseParam: param);

// On purchase success:
// 1. Verify server-side
// 2. Unlock permanently
// 3. Store entitlement

Purchase Verification Flow:

  1. User taps "Buy"
  2. Store processes payment
  3. App receives receipt / token
  4. Send token to server
  5. Server validates with store
  6. Server records entitlement
  7. App delivers content
  8. App completes / acknowledges purchase
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Consumable and Non-Consumable Purchases

Key methods:

  • buyConsumable()
  • buyNonConsumable()
  • completePurchase()
  • queryProductDetails()
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Android: Google Play Billing Library

For native Android (Kotlin), use Google Play Billing Library directly.

Setup (build.gradle):

dependencies {
  implementation 'com.android.billingclient:billing-ktx:7.1.1'
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Android: Launching a Purchase

Launching a purchase flow (Kotlin):

val billingFlowParams = BillingFlowParams.newBuilder()
  .setProductDetailsParamsList(
    listOf(
      BillingFlowParams.ProductDetailsParams.newBuilder()
        .setProductDetails(productDetails)
        .build()
    )
  )
  .build()

val result = billingClient.launchBillingFlow(activity, billingFlowParams)
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Android: Launching a Purchase

Acknowledging a purchase:

val acknowledgeParams = AcknowledgePurchaseParams.newBuilder()
  .setPurchaseToken(purchase.purchaseToken)
  .build()

billingClient.acknowledgePurchase(acknowledgeParams) { result ->
  if (result.responseCode == BillingClient.BillingResponseCode.OK) {
    deliverPremium()
  }
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Android: Launching a Purchase

Consuming a consumable:

val consumeParams = ConsumeParams.newBuilder()
  .setPurchaseToken(purchase.purchaseToken)
  .build()

billingClient.consumeAsync(consumeParams) { _, _ ->
  addCoins(100)
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

iOS: StoreKit 2

For native iOS (Swift), Apple provides StoreKit 2 with a modern async API.

Query Products (Swift):

import StoreKit

let products: [Product] = try await Product.products(
  for: ["coins_100", "premium_upgrade", "monthly_sub"]
)

for product in products {
  print("\(product.displayName): \(product.displayPrice)")
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

iOS: StoreKit 2

Purchase a Product (Swift):

func purchase(_ product: Product) async throws -> Transaction? {
  let result = try await product.purchase()

  switch result {
  case .success(let verification):
    let transaction = try checkVerified(verification)
    deliverContent(transaction)
    await transaction.finish()
    return transaction

  case .userCancelled:
    return nil

  case .pending:
    return nil

  @unknown default:
    return nil
  }
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

iOS: Transaction Verification

StoreKit 2 verification (Swift):

func checkVerified<T>(_ result: VerificationResult<T>) throws -> T {
  switch result {
  case .unverified(_, let error):
    throw error
  case .verified(let safe):
    return safe
  }
}
func listenForTransactions() async {
  for await result in Transaction.updates {
    do {
      let transaction = try checkVerified(result)
      deliverContent(transaction)
      await transaction.finish()
    } catch {
      print("Transaction failed verification")
    }
  }
}
func restorePurchases() async {
  try await AppStore.sync()
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

iOS: Transaction Verification

StoreKit 2 verifies transactions on-device using Apple's certificate chain. Production systems can also verify server-side.

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Subscription Management

Subscriptions require special handling for billing periods, grace periods, and upgrades.

Flutter Subscription Purchase:

final param = PurchaseParam(productDetails: subscriptionProduct);
_iap.buyNonConsumable(purchaseParam: param);
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Subscription Management

Key Subscription Concepts:

Concept Description
Billing Period Weekly, monthly, yearly
Free Trial N days free before first charge
Introductory Price Discounted first period
Grace Period Extra days if payment fails
Upgrade/Downgrade Switch between subscription tiers
Proration Mode How billing changes on upgrade
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Subscription Management

Checking Subscription Status:

if (purchase.productID.contains('sub_')) {
  final isActive = await server.verifySubscription(
    purchase.verificationData.serverVerificationData,
  );
  if (isActive) unlockPremium();
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Ad and IAP Best Practices

Ad Best Practices:

  • Don't show ads too frequently.
  • Use rewarded ads for opt-in engagement.
  • Preload interstitial ads before showing.
  • Use test ad IDs during development.
  • Use mediation where appropriate.
  • Respect privacy and platform rules.
  • For Iran-focused apps, evaluate local fill rate with Adivery.

IAP Best Practices:

  • Always verify purchases on a backend server.
  • Call completePurchase() / finish() after delivery.
  • Handle pending purchases.
  • Implement restore purchases.
  • Test with sandbox accounts.
  • Log purchase lifecycle events.
  • For Cafe Bazaar, verify payload, order ID, token, signature, and package name.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Ad and IAP Best Practices

Revenue strategy: Ads work best with high traffic; IAP/subscriptions work best when users clearly understand the premium value.

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Recommended Monetization Architecture

Client App

  • Shows ads
  • Starts purchase flow
  • Sends purchase token to backend
  • Shows entitlement state
  • Never decides payment validity alone

Backend Server

  • Verifies purchase / receipt / token
  • Checks duplicate order IDs
  • Stores entitlements
  • Tracks subscriptions
  • Delivers rewards safely
User → App → Store SDK → Purchase Token → Backend Verification → Entitlement

A safe monetization system treats the app as a UI layer and the backend as the source of truth.

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Summary: Key Takeaways

Ads

  • google_mobile_ads for global Flutter ads.
  • Adivery for Iran-focused Android Flutter.
  • Banner, Interstitial, Rewarded, Native.
  • Rewarded ads are best when real value.
  • Never overload the user with ads.

IAP

  • in_app_purchase for Google Play / App Store.
  • Cafe Bazaar billing for Bazaar apps.
  • Consumable, Non-Consumable, Subscription types.
  • Always verify purchases server-side.

Strategy

  • Ads for free apps with high traffic.
  • IAP for premium features and digital goods.
  • Subscriptions for recurring value.
  • Combine ads + IAP carefully.

Compliance

  • Use the correct billing system for store.
  • Test with sandbox/test accounts.
  • Implement restore purchases.
  • Provide clear pricing and subscription management.
  • Keep logs for support and fraud detect.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

References

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Thank You! 🙌

Questions?

"My app makes $0.01 per day from ads.
At this rate, I'll be a millionaire in
273,972 years."
— Every indie mobile developer

Sharif University of Technology • Fall 2027 • Ali Najimi