Flutter In-App Subscription Integration using in_app_purchase

This repository demonstrates how to integrate in-app subscriptions in a Flutter application using the in_app_purchase package. The guide includes step-by-step instructions for setting up in-app subscriptions for both Google Play Store and Apple App Store, along with introductory offers.

Features

• Subscription handling for both iOS and Android.
• Fetching products and subscription plans from stores.
• Managing purchases and handling billing.
• Handling introductory offers on both stores.

Prerequisites

1. Flutter SDK: Make sure Flutter is installed. Installation Guide
2. Google Play Console: To configure in-app purchases for Android.
3. App Store Connect: To configure in-app purchases for iOS.

Setup

1. Add Dependencies

In your pubspec.yaml, add the following dependencies:

dependencies:
  flutter:
    sdk: flutter
  in_app_purchase: ^3.0.6

2. Configure iOS

• In Xcode, go to Signing & Capabilities and enable and create product In-App Subscription.
• Ensure that your app’s bundle ID matches the one registered in App Store Connect.
• Set up your In-App Purchase items in App Store Connect.

Enable StoreKit Testing

For local testing, you can enable StoreKit testing using Xcode:

• Open the ios project in Xcode.
• In the Scheme Editor, select Run, then go to Options.
• Under StoreKit Configuration, select the StoreKit configuration file for testing.

3. Configure Android

• Open android/app/build.gradle and ensure you have:

  def billing_version = "5.0.0"

• Add the following permission in AndroidManifest.xml:

  <uses-permission android:name="com.android.vending.BILLING" />

• Set up In-App Purchase products in the Google Play Console under Monetize > Products > Subscriptions.

4. Initialize in_app_purchase

Add the initialization code to your app:

import 'package:flutter/material.dart';
import 'package:in_app_purchase/in_app_purchase.dart';

void main() {
  WidgetsFlutterBinding.ensureInitialized();
  InAppPurchase.instance.isAvailable().then((isAvailable) {
    if (isAvailable) {
      // Proceed with fetching and displaying products
    } else {
      // Handle store unavailability
    }
  });
  runApp(MyApp());
}

5. Fetch Available Subscriptions

Future<void> fetchSubscriptions() async {
  final bool available = await InAppPurchase.instance.isAvailable();
  if (!available) {
    // Handle store not available
    return;
  }

  const Set<String> _kIds = <String>{'subscription_id_1', 'subscription_id_2'};
  final ProductDetailsResponse response = await InAppPurchase.instance.queryProductDetails(_kIds);
  if (response.notFoundIDs.isNotEmpty) {
    // Handle missing products
  }
  final List<ProductDetails> products = response.productDetails;
  // Process and display the available subscriptions
}

6. Handling Purchases

void handlePurchaseUpdates() {
  final Stream<List<PurchaseDetails>> purchaseUpdates = InAppPurchase.instance.purchaseStream;
  purchaseUpdates.listen((purchases) {
    for (PurchaseDetails purchase in purchases) {
      if (purchase.status == PurchaseStatus.pending) {
        // Handle pending purchase
      } else if (purchase.status == PurchaseStatus.purchased) {
        // Verify purchase and grant entitlement
        InAppPurchase.instance.completePurchase(purchase);
      } else if (purchase.status == PurchaseStatus.error) {
        // Handle purchase error
      }
    }
  });
}

Creating Introductory Offers

App Store (iOS)

1. Log in to App Store Connect.
2. Navigate to My Apps > Your App > Features > In-App Purchases.
3. Create a new subscription or select an existing one.
4. Scroll down to Subscription Prices and click Add Introductory Offer.
5. Choose the introductory offer type (free trial, pay-as-you-go, pay-up-front), and set the pricing details.

Play Store (Android)

1. Log in to the Google Play Console.
2. Navigate to Monetize > Products > Subscriptions.
3. Select your subscription product.
4. In the Introductory pricing section, click Add.
5. Set up the introductory pricing duration and price.

Links

• in_app_purchase package documentation
• App Store In-App Purchases Guide
• Google Play Billing Guide

License

This project is licensed under the MIT License. See the LICENSE file for details.