iOS Swift Decodable: Error: Cannot invoke initializer for type with no arguments

Question

我在初始化结构时遇到错误，请参阅下面的屏幕截图。调试后我发现在结构中包含 review 变量会产生问题。我不知道我做错了什么。谁能帮帮我？

发送

我正在复制代码，以防您需要尝试一下

import UIKit

struct RootValue : Decodable {
    private enum CodingKeys : String, CodingKey {
        case success = "success"
        case content = "data"
        case errors = "errors"
    }
    let success: Bool
    let content : [ProfileValue]
    let errors: [String]
}

struct ProfileValue : Decodable {
    private enum CodingKeys : String, CodingKey {
        case id = "id"
        case name = "name"
        case review = "review" // including this gives error
    }

    var id: Int = 0
    var name: String = ""
    var review: ReviewValues // including this gives error
}

struct ReviewValues : Decodable{
    private enum CodingKeys : String, CodingKey {
        case place = "place"
    }

    var place: String = ""
}

class ViewController: UIViewController {

    var profileValue = ProfileValue()

    override func viewDidLoad() {
        super.viewDidLoad()
    }
}

Answer 1

您的 ProfileValue 结构没有 review 属性的默认值。这就是编译器不高兴的原因，因为您试图创建 ProfileValue 的实例而不为所有非可选属性提供默认值。

附带说明一下，您所有的编码键枚举值都与属性名称匹配。如果名称相同，则无需包含编码键枚举。

Answer 2

评论没有默认值，您需要更改此

var profileValue = ProfileValue()

至

var profileValue:ProfileValue?

或

var review: ReviewValues?

或

在 ProfileValue 结构

中提供 init 方法

Answer 3

向您的 ProfileValue 结构添加一个初始化：

struct ProfileValue : Decodable {
  private enum CodingKeys : String, CodingKey {
    case id = "id"
    case name = "name"
    case review = "review" // including this gives error
  }

  var id: Int = 0
  var name: String = ""
  var review: ReviewValues // including this gives error

  init() {
    self.review = ReviewValues()
  }
}

Answer 4

添加默认init方法，在codable modal中提供默认init方法来创建编码对象。

struct Modal: Codable {

    var status: String?
    var result : [Result?]?

    // To provide the default init method to create the encoded object

    init?() {
        return nil
    }

    private enum CodingKeys: String, CodingKey {
        case status = "status"
        case result = "result"
    }
}

iOS Swift Decodable: Error: Cannot invoke initializer for type with no arguments

iOS Swift Decodable: Error: Cannot invoke initializer for type with no arguments

ios

swift

swift4

decodable