What is Flutter in app purchase package on pub.dev and How to use it!

Flutter in app purchase is used for purchase in google playstore(Android) and apple app store(iOS). This plugin supports in-app purchases (IAP) through an underlying store, which can be the App Store (on iOS and macOS) or Google Play (on Android).


A Flutter plugin for in-app purchases. Exposes APIs for making in-app purchases through the App Store and Google Play.

Used For
Android
iOS
macOS

Support 
SDK 16+ 11.0+ 10.15+

Features

Use this plugin in your Flutter app to:Show in-app products that are available for sale from the underlying store. Products can include consumables, permanent upgrades, and subscriptions.
Load in-app products that the user owns.
Send the user to the underlying store to purchase products.
Present a UI for redeeming subscription offer codes. (iOS 14 only)

Use this package as a library

Depend on it

Run this command:

With Flutter:

 $ flutter pub add in_app_purchase

This will add a line like this to your package's pubspec.yaml (and run an implicit flutter pub get):

dependencies:
  in_app_purchase: ^3.1.5

Alternatively, your editor might support flutter pub get. Check the docs for your editor to learn more.

Import it

Now in your Dart code, you can use:

import 'package:in_app_purchase/in_app_purchase.dart';

Full Use Case Example:

example/lib/main.dart

// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'dart:async';
import 'dart:io';

import 'package:flutter/material.dart';
import 'package:in_app_purchase/in_app_purchase.dart';
import 'package:in_app_purchase_android/billing_client_wrappers.dart';
import 'package:in_app_purchase_android/in_app_purchase_android.dart';
import 'package:in_app_purchase_storekit/in_app_purchase_storekit.dart';
import 'package:in_app_purchase_storekit/store_kit_wrappers.dart';

import 'consumable_store.dart';

void main() {
  WidgetsFlutterBinding.ensureInitialized();

  runApp(_MyApp());
}

// Auto-consume must be true on iOS.
// To try without auto-consume on another platform, change `true` to `false` here.
final bool _kAutoConsume = Platform.isIOS || true;

const String _kConsumableId = 'consumable';
const String _kUpgradeId = 'upgrade';
const String _kSilverSubscriptionId = 'subscription_silver';
const String _kGoldSubscriptionId = 'subscription_gold';
const List<String> _kProductIds = <String>[
  _kConsumableId,
  _kUpgradeId,
  _kSilverSubscriptionId,
  _kGoldSubscriptionId,
];

class _MyApp extends StatefulWidget {
  @override
  State<_MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<_MyApp> {
  final InAppPurchase _inAppPurchase = InAppPurchase.instance;
  late StreamSubscription<List<PurchaseDetails>> _subscription;
  List<String> _notFoundIds = <String>[];
  List<ProductDetails> _products = <ProductDetails>[];
  List<PurchaseDetails> _purchases = <PurchaseDetails>[];
  List<String> _consumables = <String>[];
  bool _isAvailable = false;
  bool _purchasePending = false;
  bool _loading = true;
  String? _queryProductError;

  @override
  void initState() {
    final Stream<List<PurchaseDetails>> purchaseUpdated =
        _inAppPurchase.purchaseStream;
    _subscription =
        purchaseUpdated.listen((List<PurchaseDetails> purchaseDetailsList) {
      _listenToPurchaseUpdated(purchaseDetailsList);
    }, onDone: () {
      _subscription.cancel();
    }, onError: (Object error) {
      // handle error here.
    });
    initStoreInfo();
    super.initState();
  }

  Future<void> initStoreInfo() async {
    final bool isAvailable = await _inAppPurchase.isAvailable();
    if (!isAvailable) {
      setState(() {
        _isAvailable = isAvailable;
        _products = <ProductDetails>[];
        _purchases = <PurchaseDetails>[];
        _notFoundIds = <String>[];
        _consumables = <String>[];
        _purchasePending = false;
        _loading = false;
      });
      return;
    }

    if (Platform.isIOS) {
      final InAppPurchaseStoreKitPlatformAddition iosPlatformAddition =
          _inAppPurchase
              .getPlatformAddition<InAppPurchaseStoreKitPlatformAddition>();
      await iosPlatformAddition.setDelegate(ExamplePaymentQueueDelegate());
    }

    final ProductDetailsResponse productDetailResponse =
        await _inAppPurchase.queryProductDetails(_kProductIds.toSet());
    if (productDetailResponse.error != null) {
      setState(() {
        _queryProductError = productDetailResponse.error!.message;
        _isAvailable = isAvailable;
        _products = productDetailResponse.productDetails;
        _purchases = <PurchaseDetails>[];
        _notFoundIds = productDetailResponse.notFoundIDs;
        _consumables = <String>[];
        _purchasePending = false;
        _loading = false;
      });
      return;
    }

    if (productDetailResponse.productDetails.isEmpty) {
      setState(() {
        _queryProductError = null;
        _isAvailable = isAvailable;
        _products = productDetailResponse.productDetails;
        _purchases = <PurchaseDetails>[];
        _notFoundIds = productDetailResponse.notFoundIDs;
        _consumables = <String>[];
        _purchasePending = false;
        _loading = false;
      });
      return;
    }

    final List<String> consumables = await ConsumableStore.load();
    setState(() {
      _isAvailable = isAvailable;
      _products = productDetailResponse.productDetails;
      _notFoundIds = productDetailResponse.notFoundIDs;
      _consumables = consumables;
      _purchasePending = false;
      _loading = false;
    });
  }

  @override
  void dispose() {
    if (Platform.isIOS) {
      final InAppPurchaseStoreKitPlatformAddition iosPlatformAddition =
          _inAppPurchase
              .getPlatformAddition<InAppPurchaseStoreKitPlatformAddition>();
      iosPlatformAddition.setDelegate(null);
    }
    _subscription.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final List<Widget> stack = <Widget>[];
    if (_queryProductError == null) {
      stack.add(
        ListView(
          children: <Widget>[
            _buildConnectionCheckTile(),
            _buildProductList(),
            _buildConsumableBox(),
            _buildRestoreButton(),
          ],
        ),
      );
    } else {
      stack.add(Center(
        child: Text(_queryProductError!),
      ));
    }
    if (_purchasePending) {
      stack.add(
        // TODO(goderbauer): Make this const when that's available on stable.
        // ignore: prefer_const_constructors
        Stack(
          children: const <Widget>[
            Opacity(
              opacity: 0.3,
              child: ModalBarrier(dismissible: false, color: Colors.grey),
            ),
            Center(
              child: CircularProgressIndicator(),
            ),
          ],
        ),
      );
    }

    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('IAP Example'),
        ),
        body: Stack(
          children: stack,
        ),
      ),
    );
  }

  Card _buildConnectionCheckTile() {
    if (_loading) {
      return const Card(child: ListTile(title: Text('Trying to connect...')));
    }
    final Widget storeHeader = ListTile(
      leading: Icon(_isAvailable ? Icons.check : Icons.block,
          color: _isAvailable
              ? Colors.green
              : ThemeData.light().colorScheme.error),
      title:
          Text('The store is ${_isAvailable ? 'available' : 'unavailable'}.'),
    );
    final List<Widget> children = <Widget>[storeHeader];

    if (!_isAvailable) {
      children.addAll(<Widget>[
        const Divider(),
        ListTile(
          title: Text('Not connected',
              style: TextStyle(color: ThemeData.light().colorScheme.error)),
          subtitle: const Text(
              'Unable to connect to the payments processor. Has this app been configured correctly? See the example README for instructions.'),
        ),
      ]);
    }
    return Card(child: Column(children: children));
  }

  Card _buildProductList() {
    if (_loading) {
      return const Card(
          child: ListTile(
              leading: CircularProgressIndicator(),
              title: Text('Fetching products...')));
    }
    if (!_isAvailable) {
      return const Card();
    }
    const ListTile productHeader = ListTile(title: Text('Products for Sale'));
    final List<ListTile> productList = <ListTile>[];
    if (_notFoundIds.isNotEmpty) {
      productList.add(ListTile(
          title: Text('[${_notFoundIds.join(", ")}] not found',
              style: TextStyle(color: ThemeData.light().colorScheme.error)),
          subtitle: const Text(
              'This app needs special configuration to run. Please see example/README.md for instructions.')));
    }

    // This loading previous purchases code is just a demo. Please do not use this as it is.
    // In your app you should always verify the purchase data using the `verificationData` inside the [PurchaseDetails] object before trusting it.
    // We recommend that you use your own server to verify the purchase data.
    final Map<String, PurchaseDetails> purchases =
        Map<String, PurchaseDetails>.fromEntries(
            _purchases.map((PurchaseDetails purchase) {
      if (purchase.pendingCompletePurchase) {
        _inAppPurchase.completePurchase(purchase);
      }
      return MapEntry<String, PurchaseDetails>(purchase.productID, purchase);
    }));
    productList.addAll(_products.map(
      (ProductDetails productDetails) {
        final PurchaseDetails? previousPurchase = purchases[productDetails.id];
        return ListTile(
          title: Text(
            productDetails.title,
          ),
          subtitle: Text(
            productDetails.description,
          ),
          trailing: previousPurchase != null
              ? IconButton(
                  onPressed: () => confirmPriceChange(context),
                  icon: const Icon(Icons.upgrade))
              : TextButton(
                  style: TextButton.styleFrom(
                    backgroundColor: Colors.green[800],
                    // TODO(darrenaustin): Migrate to new API once it lands in stable: https://github.com/flutter/flutter/issues/105724
                    // ignore: deprecated_member_use
                    primary: Colors.white,
                  ),
                  onPressed: () {
                    late PurchaseParam purchaseParam;

                    if (Platform.isAndroid) {
                      // NOTE: If you are making a subscription purchase/upgrade/downgrade, we recommend you to
                      // verify the latest status of you your subscription by using server side receipt validation
                      // and update the UI accordingly. The subscription purchase status shown
                      // inside the app may not be accurate.
                      final GooglePlayPurchaseDetails? oldSubscription =
                          _getOldSubscription(productDetails, purchases);

                      purchaseParam = GooglePlayPurchaseParam(
                          productDetails: productDetails,
                          changeSubscriptionParam: (oldSubscription != null)
                              ? ChangeSubscriptionParam(
                                  oldPurchaseDetails: oldSubscription,
                                  prorationMode:
                                      ProrationMode.immediateWithTimeProration,
                                )
                              : null);
                    } else {
                      purchaseParam = PurchaseParam(
                        productDetails: productDetails,
                      );
                    }

                    if (productDetails.id == _kConsumableId) {
                      _inAppPurchase.buyConsumable(
                          purchaseParam: purchaseParam,
                          autoConsume: _kAutoConsume);
                    } else {
                      _inAppPurchase.buyNonConsumable(
                          purchaseParam: purchaseParam);
                    }
                  },
                  child: Text(productDetails.price),
                ),
        );
      },
    ));

    return Card(
        child: Column(
            children: <Widget>[productHeader, const Divider()] + productList));
  }

  Card _buildConsumableBox() {
    if (_loading) {
      return const Card(
          child: ListTile(
              leading: CircularProgressIndicator(),
              title: Text('Fetching consumables...')));
    }
    if (!_isAvailable || _notFoundIds.contains(_kConsumableId)) {
      return const Card();
    }
    const ListTile consumableHeader =
        ListTile(title: Text('Purchased consumables'));
    final List<Widget> tokens = _consumables.map((String id) {
      return GridTile(
        child: IconButton(
          icon: const Icon(
            Icons.stars,
            size: 42.0,
            color: Colors.orange,
          ),
          splashColor: Colors.yellowAccent,
          onPressed: () => consume(id),
        ),
      );
    }).toList();
    return Card(
        child: Column(children: <Widget>[
      consumableHeader,
      const Divider(),
      GridView.count(
        crossAxisCount: 5,
        shrinkWrap: true,
        padding: const EdgeInsets.all(16.0),
        children: tokens,
      )
    ]));
  }

  Widget _buildRestoreButton() {
    if (_loading) {
      return Container();
    }

    return Padding(
      padding: const EdgeInsets.all(4.0),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.end,
        children: <Widget>[
          TextButton(
            style: TextButton.styleFrom(
              backgroundColor: Theme.of(context).primaryColor,
              // TODO(darrenaustin): Migrate to new API once it lands in stable: https://github.com/flutter/flutter/issues/105724
              // ignore: deprecated_member_use
              primary: Colors.white,
            ),
            onPressed: () => _inAppPurchase.restorePurchases(),
            child: const Text('Restore purchases'),
          ),
        ],
      ),
    );
  }

  Future<void> consume(String id) async {
    await ConsumableStore.consume(id);
    final List<String> consumables = await ConsumableStore.load();
    setState(() {
      _consumables = consumables;
    });
  }

  void showPendingUI() {
    setState(() {
      _purchasePending = true;
    });
  }

  Future<void> deliverProduct(PurchaseDetails purchaseDetails) async {
    // IMPORTANT!! Always verify purchase details before delivering the product.
    if (purchaseDetails.productID == _kConsumableId) {
      await ConsumableStore.save(purchaseDetails.purchaseID!);
      final List<String> consumables = await ConsumableStore.load();
      setState(() {
        _purchasePending = false;
        _consumables = consumables;
      });
    } else {
      setState(() {
        _purchases.add(purchaseDetails);
        _purchasePending = false;
      });
    }
  }

  void handleError(IAPError error) {
    setState(() {
      _purchasePending = false;
    });
  }

  Future<bool> _verifyPurchase(PurchaseDetails purchaseDetails) {
    // IMPORTANT!! Always verify a purchase before delivering the product.
    // For the purpose of an example, we directly return true.
    return Future<bool>.value(true);
  }

  void _handleInvalidPurchase(PurchaseDetails purchaseDetails) {
    // handle invalid purchase here if  _verifyPurchase` failed.
  }

  Future<void> _listenToPurchaseUpdated(
      List<PurchaseDetails> purchaseDetailsList) async {
    for (final PurchaseDetails purchaseDetails in purchaseDetailsList) {
      if (purchaseDetails.status == PurchaseStatus.pending) {
        showPendingUI();
      } else {
        if (purchaseDetails.status == PurchaseStatus.error) {
          handleError(purchaseDetails.error!);
        } else if (purchaseDetails.status == PurchaseStatus.purchased ||
            purchaseDetails.status == PurchaseStatus.restored) {
          final bool valid = await _verifyPurchase(purchaseDetails);
          if (valid) {
            deliverProduct(purchaseDetails);
          } else {
            _handleInvalidPurchase(purchaseDetails);
            return;
          }
        }
        if (Platform.isAndroid) {
          if (!_kAutoConsume && purchaseDetails.productID == _kConsumableId) {
            final InAppPurchaseAndroidPlatformAddition androidAddition =
                _inAppPurchase.getPlatformAddition<
                    InAppPurchaseAndroidPlatformAddition>();
            await androidAddition.consumePurchase(purchaseDetails);
          }
        }
        if (purchaseDetails.pendingCompletePurchase) {
          await _inAppPurchase.completePurchase(purchaseDetails);
        }
      }
    }
  }

  Future<void> confirmPriceChange(BuildContext context) async {
    if (Platform.isAndroid) {
      final InAppPurchaseAndroidPlatformAddition androidAddition =
          _inAppPurchase
              .getPlatformAddition<InAppPurchaseAndroidPlatformAddition>();
      final BillingResultWrapper priceChangeConfirmationResult =
          await androidAddition.launchPriceChangeConfirmationFlow(
        sku: 'purchaseId',
      );
      if (context.mounted) {
        if (priceChangeConfirmationResult.responseCode == BillingResponse.ok) {
          ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
            content: Text('Price change accepted'),
          ));
        } else {
          ScaffoldMessenger.of(context).showSnackBar(SnackBar(
            content: Text(
              priceChangeConfirmationResult.debugMessage ??
                  'Price change failed with code ${priceChangeConfirmationResult.responseCode}',
            ),
          ));
        }
      }
    }
    if (Platform.isIOS) {
      final InAppPurchaseStoreKitPlatformAddition iapStoreKitPlatformAddition =
          _inAppPurchase
              .getPlatformAddition<InAppPurchaseStoreKitPlatformAddition>();
      await iapStoreKitPlatformAddition.showPriceConsentIfNeeded();
    }
  }

  GooglePlayPurchaseDetails? _getOldSubscription(
      ProductDetails productDetails, Map<String, PurchaseDetails> purchases) {
    // This is just to demonstrate a subscription upgrade or downgrade.
    // This method assumes that you have only 2 subscriptions under a group, 'subscription_silver' & 'subscription_gold'.
    // The 'subscription_silver' subscription can be upgraded to 'subscription_gold' and
    // the 'subscription_gold' subscription can be downgraded to 'subscription_silver'.
    // Please remember to replace the logic of finding the old subscription Id as per your app.
    // The old subscription is only required on Android since Apple handles this internally
    // by using the subscription group feature in iTunesConnect.
    GooglePlayPurchaseDetails? oldSubscription;
    if (productDetails.id == _kSilverSubscriptionId &&
        purchases[_kGoldSubscriptionId] != null) {
      oldSubscription =
          purchases[_kGoldSubscriptionId]! as GooglePlayPurchaseDetails;
    } else if (productDetails.id == _kGoldSubscriptionId &&
        purchases[_kSilverSubscriptionId] != null) {
      oldSubscription =
          purchases[_kSilverSubscriptionId]! as GooglePlayPurchaseDetails;
    }
    return oldSubscription;
  }
}

/// Example implementation of the
/// [`SKPaymentQueueDelegate`](https://developer.apple.com/documentation/storekit/skpaymentqueuedelegate?language=objc).
///
/// The payment queue delegate can be implementated to provide information
/// needed to complete transactions.
class ExamplePaymentQueueDelegate implements SKPaymentQueueDelegateWrapper {
  @override
  bool shouldContinueTransaction(
      SKPaymentTransactionWrapper transaction, SKStorefrontWrapper storefront) {
    return true;
  }

  @override
  bool shouldShowPriceConsent() {
    return false;
  }



For Using Flutter In app purchase plugin/package from official click here.

Flutter in_app_purchase    Package

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