子类化 JSON (Swift) 时出错

Question

我对在 Swift 中处理 JSON 数据还很陌生，我正在尝试对一些产品进行子类化。我不是要编码转储，但我想给你整个画面。我有三个相同的错误：从这里抛出的错误没有得到处理它们发生在required init。提前致谢。代码如下：

import UIKit

class Product: Decodable {
    var category: String = ""
    var material: String = ""

    init() {

    }
}

class TelephoneWithCord: Product {

    var sku: Double
    var isNew: Bool

    private enum CodingKeys: String, CodingKey {
        case sku = "sku"
        case isNew = "isNew"
    }

    required init(from decoder: Decoder) {

        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.sku = try container.decode(Double.self, forKey: .sku)
        self.isNew = try container.decode(Bool.self, forKey: .isNew)
    }
}

let json = """

{
    "category" : "home",
    "material" : "plastic",
    "sku" : 264221,
    "isNew" : true
}

""".data(using: .utf8)!

let telephoneWithCord = try! JSONDecoder().decode(TelephoneWithCord.self, from: json)

telephoneWithCord.category
telephoneWithCord.material
telephoneWithCord.sku
telephoneWithCord.isNew

Answer 1

“抛出的错误”可能是有关如何解决此问题的提示。将throws 添加到required init。另外，不要忘记调用super 以正确初始化您的代码，否则您将收到另一个错误。试试这些改变...

required init(from decoder: Decoder) throws {  // add throws to eliminate errors

    let container = try decoder.container(keyedBy: CodingKeys.self)
    self.sku = try container.decode(Double.self, forKey: .sku)
    self.isNew = try container.decode(Bool.self, forKey: .isNew)
    try super.init(from: decoder)  // calling super for proper intialization of code
}

附带说明：如果您的 sku 中没有使用任何小数点，那么您应该将类​​型更改为 Int 而不是 Double。