Parse Apple receipt example

Example.swift

private func parseReceipt(_ json : Dictionary<String, Any>) {
        // It's the most simple way to get latest expiration date. Consider this code as for learning purposes. Do not use current code in production apps.
        guard let receipts_array = json["latest_receipt_info"] as? [Dictionary<String, Any>] else {
            self.refreshSubscriptionFailureBlock?(nil)
            self.cleanUpRefeshReceiptBlocks()
            return
        }
        for receipt in receipts_array {
            let productID = receipt["product_id"] as! String 
            let formatter = DateFormatter()
            formatter.dateFormat = "yyyy-MM-dd HH:mm:ss VV"
            if let date = formatter.date(from: receipt["expires_date"] as! String) {
                if date > Date() {
                    // do not save expired date to user defaults to avoid overwriting with expired date
                    UserDefaults.standard.set(date, forKey: productID)
                }
            }
        }
        self.refreshSubscriptionSuccessBlock?()
        self.cleanUpRefeshReceiptBlocks()
    }