SwiftyStoreKit - 何时执行收据验证

如何解决SwiftyStoreKit - 何时执行收据验证

我正在使用 SwiftyStoreKit 来执行订阅：

private func subscribeUser(withId subscriptionId: String) {
    SwiftyStoreKit.purchaseProduct(subscriptionId,atomically: false) { result in
        switch result {
        case .success(let product):
            
            if product.needsFinishTransaction {
                SwiftyStoreKit.finishTransaction(product.transaction)
            }
            
            // Get the receipt
            SwiftyStoreKit.fetchReceipt(forceRefresh: true) { result in
                switch result {
                case .success(let receiptData):
                    // Encrypt the receipt
                    let encryptedReceipt = receiptData.base64EncodedString(options: [])
                    
                    // Set up verification url
                    let url = "https://myUrl/verifyReceipt"
                    
                    // Send receipt to server
                    APIConnect.verifyReceipt(
                        url: url,params: ["receipt" : encryptedReceipt],completion: self.processSubscription)
                    
                    
                case .error(let error):
                    print("SUBSCRIPTIONPAYMENTVC | subscribeUser | Fetch receipt Failed: \(error)")
                }
            }
            
        case .error(let error):
            switch error.code {
                // alert user accordingly
            }
        }
    }
}

在收据发送到我们的服务器并验证后，响应被处理：

func processSubscription(receiptJSON: JSON) {
    print("SUBSCRIPTIONPAYMENTVC | verifySubscription | Done Verifying Subscription")
    
    // Check response
    if receiptJSON["status"] > 0 {
        
        // alert user accordingly
        
    } else {
    
        // Get data from receipt
        let lastReceiptIndex = receiptJSON["latest_receipt_info"].arrayValue.count - 1
        
        // Set up varibles
        productId = receiptJSON["latest_receipt_info"][lastReceiptIndex]["product_id"].stringValue
        originalTransactionId = receiptJSON["latest_receipt_info"][lastReceiptIndex]["original_transaction_id"].stringValue
        startDate = receiptJSON["latest_receipt_info"][lastReceiptIndex]["original_purchase_date_ms"].stringValue
        endDate = receiptJSON["latest_receipt_info"][lastReceiptIndex]["expires_date_ms"].stringValue
        latestReceipt = receiptJSON["latest_receipt"].stringValue
        
        // Add user to database
        addUserToDB()
        
    }
}

但是，即使 processSubscription 可能收到状态 > 0，用户是否也已被收费？我是否在错误的时间调用收据验证？购买究竟发生在何处，如何通过验证阻止购买？