in_app_purchase application setup Flutter IOS 内购示范代码

in_app_purchase application setup

import 'dart:async';

import 'package:Flutter/material.dart';
import 'package:in_app_purchase/in_app_purchase.dart';
import 'dart:io';
import 'package:in_app_purchase_android/in_app_purchase_android.dart';


void main() {
 runApp(
 const MaterialApp(
 home: Purchase()
 ),
 );
}


const String testID = 'book_test';

class Purchase extends StatefulWidget {

 const Purchase({Key? key}) : super(key: key);

 @override
 _PurchaseState createState() => _PurchaseState();

}

class _PurchaseState extends State<Purchase> {

 // Instantiates inAppPurchase
 final InAppPurchase _iap = InAppPurchase.instance;

 // checks if the API is available on this device
 bool _isAvailable = false;

 // keeps a list of products queried from Playstore or app store
 List<ProductDetails> _products = [];

 // List of users past purchases
 List<PurchaseDetails> _purchases = [];

 // subscription that listens to a stream of updates to purchase details
 late StreamSubscription _subscription;

 // used to represents consumable credits the user can buy
 int _coins = 0;


 Future<void> _initialize() async {

 // Check availability of InApp Purchases
 _isAvailable = await _iap.isAvailable();


 // perform our async calls only when in-app purchase is available
 if(_isAvailable){

 await _getUserProducts();
 await _getPastPurchases();
 _verifyPurchases();

 // listen to new purchases and rebuild the widget whenever
 // there is a new purchase after adding the new purchase to our
 // purchase list

 _subscription = _iap.purchaseStream.listen((data)=> setState((){

 _purchases.addAll(data);
 _verifyPurchases();
 }));

 }
 }


 // Method to retrieve product list
 Future<void> _getUserProducts() async {
 Set<String> ids = {testID};
 ProductDetailsResponse response = await _iap.queryProductDetails(ids);

 setState(() {
 _products = response.productDetails;
 });
 }

 // Method to retrieve users past purchase
 Future<void> _getPastPurchases() async {
 QueryPurchaseDetailsResponse response = await _iap.queryPastPurchases();

 for(PurchaseDetails purchase in response.pastPurchases){
 if(Platform.isIOS){
 _iap.completePurchase(purchase);
 }
 }
 setState(() {
 _purchases = response.pastPurchases;
 });
 }

 // checks if a user has purchased a certain product
 PurchaseDetails _hasUserPurchased(String productID){
 return _purchases.firstWhere((purchase) => purchase.productID == productID);
 }


 // Method to check if the product has been purchased already or not.
 void _verifyPurchases(){
 PurchaseDetails purchase = _hasUserPurchased(testID);
 if(purchase.status == PurchaseStatus.purchased){
 _coins = 10;
 }
 }

 // Method to purchase a product
 void _buyProduct(ProductDetails prod){
 final PurchaseParam purchaseParam = PurchaseParam(productDetails: prod);
 _iap.buyConsumable(purchaseParam: purchaseParam, autoConsume: false);
 }


 void spendCoins(PurchaseDetails purchase) async {
 setState(() {
 _coins--;
 });
 if(_coins == 0 ){
 var res = await _iap.consumePurchase(purchase);
 }
 }

 @override
 void initState() {
 _initialize();
 super.initState();
 }

 @override
 void dispose() {

 // cancelling the subscription
 _subscription.cancel();

 super.dispose();
 }


 @override
 Widget build(BuildContext context) {
 return Scaffold(
 appBar: AppBar(
 title: Text(_isAvailable ? 'Product Available': 'No Product Available'),
 ),
 body: Center(
 child: Column(
 children: [

 // Looping over products from app store or Playstore
 // for each product, determine if the user has a past purchase for it
 for (var product in _products)

 // If purchase exists
 if(_hasUserPurchased(product.id) != null)
  ...[
  Text('$_coins', style: const TextStyle(fontSize: 30),),
  ElevatedButton(
  onPressed: ()=> spendCoins(_hasUserPurchased(product.id)),
  child: const Text('Consume')),
  ]

 // If not purchased exist
 else ...[
  Text(product.title,),
  Text(product.description),
  Text(product.price),
  ElevatedButton(
  onPressed: () => _buyProduct(product),
  child: const Text(''))
 ]
 ],
 ),
 ),
 );
 }
}