ios - 尝试在应用程序购买中实现，为 NSArray 获取错误“消息发送到已释放实例”

Question

我正在使用应用内购买教程中的代码。

错误 [__NSArrayI objectAtIndex:]: message sent to deallocated instance发生在这里：

[self purchaseMyProduct:[validProducts objectAtIndex:0]];

这里是validProducts使用的地方。

-(void)productsRequest:(SKProductsRequest *)request
    didReceiveResponse:(SKProductsResponse *)response
{
    SKProduct *validProduct = nil;
    int count = [response.products count];
    if (count>0) {


        validProducts = response.products;
        validProduct = [response.products objectAtIndex:0];
        if (![validProduct.productIdentifier
              isEqualToString:@"facePuppetsSave"]) {

        UIAlertView *tmp = [[UIAlertView alloc]
                            initWithTitle:@"Not Available"
                            message:@"No products to purchase"
                            delegate:self
                            cancelButtonTitle:nil
                            otherButtonTitles:@"Ok", nil];
        [tmp show];
    }    
}
}

我看了一些类似的SO问题，说要添加dealloc

[[SKPaymentQueue defaultQueue] removeTransactionObserver:self];

productsRequest.delegate = nil;
[productsRequest cancel];
productsRequest = nil;

但没有任何改变。

以下是其他方法，如果它们是相关的。

- (void)fetchAvailableProducts {

   // NSSet *productIdentifiers = [NSSet setWithObject:@"facePuppetsSave"] ,nil];
    productsRequest = [[SKProductsRequest alloc] initWithProductIdentifiers:[NSSet setWithObject:@"facePuppetsSave"]];
    productsRequest.delegate = self;
    [productsRequest start];

}

- (BOOL)canMakePurchases
{
    return [SKPaymentQueue canMakePayments];
}

- (void)purchaseMyProduct:(SKProduct*)product{
    if ([self canMakePurchases]) {

        SKPayment *payment = [SKPayment paymentWithProduct:product];
        [[SKPaymentQueue defaultQueue] addTransactionObserver:self];
        [[SKPaymentQueue defaultQueue] addPayment:payment];
    }
    else{
        UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:
                                  @"Purchases are disabled in your device" message:nil delegate:
                                  self cancelButtonTitle:@"Ok" otherButtonTitles: nil];
        [alertView show];
    }


}



#pragma mark StoreKit Delegate

-(void)paymentQueue:(SKPaymentQueue *)queue
updatedTransactions:(NSArray *)transactions {
    for (SKPaymentTransaction *transaction in transactions) {
        switch (transaction.transactionState) {
            case SKPaymentTransactionStatePurchasing:
                NSLog(@"Purchasing");
                break;
            case SKPaymentTransactionStatePurchased:
                if ([transaction.payment.productIdentifier
                     isEqualToString:@"facePuppetsSave"]) {
                    NSLog(@"Purchased ");
                    UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:
                                              @"Purchase is completed succesfully" message:nil delegate:
                                              self cancelButtonTitle:@"Ok" otherButtonTitles: nil];
                    [alertView show];
                }
                [[SKPaymentQueue defaultQueue] finishTransaction:transaction];
                break;
            case SKPaymentTransactionStateRestored:
                NSLog(@"Restored ");
                [[SKPaymentQueue defaultQueue] finishTransaction:transaction];
                break;
            case SKPaymentTransactionStateFailed:
                NSLog(@"Purchase failed ");
                break;
            default:
                break;
        }
    }
}