class ProductsDescription: Decodable {
    var data: [Product]

    enum CodingKeys: String, CodingKey {
        case data
        case products
    }
    enum ProductsKeys: String, CodingKey {
        case products
    }


    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        if let multiple = try? container.decode([Product].self, forKey: .data) {
            self.data = multiple
        } else {
            let nestedContainer = try container.nestedContainer(keyedBy: CodingKeys.self, forKey: .data)
            let subvalues = try nestedContainer.decode([Product].self, forKey: .products)
            self.data = subvalues
        }
    }
}

struct Product: Codable {
    let options: [Option]

    struct Option: Codable {
        let value: String
        let key: Int
    }
}


let jsonMultiple = """
{"data":[{"options":[{"value":"MULTIPLE","key":111}]}]}
"""
let jsonSingle = """
{"data":{"products":[{"options":[{"value":"SINGLE","key":333}]}]}}
"""



func tryWith(json: String) {

    let data = json.data(using: .utf8)!
    let dataObj = try! JSONSerialization.jsonObject(with: data, options: [])
    let printedData = try! JSONSerialization.data(withJSONObject: dataObj, options: .prettyPrinted)
    let toPrint = String(data: printedData, encoding: .utf8)!
    print(toPrint)
    do {
        let products = try JSONDecoder().decode(ProductsDescription.self, from: data)
        print(products)

        products.data.forEach{ print($0) }
    } catch {
        print("Error: \(error)")
    }
}

print("-----")
tryWith(json: jsonMultiple)
print("-----")
tryWith(json: jsonSingle)
print("-----")