ios - Codable - 如何用空数组声明可选数组类型

Question

struct Data: Codable {
  let name: String?
  let dataArray: [User] = [User]()
}

dataArray 是可选的，所以我想用空分配它但我的 Codable 失败了？我能知道如何实现这一点吗，我可以在不分配它的情况下将其声明为可选。但我想实现这一目标。

Answer 1

您应该手动解码您的对象:

struct Data: Codable {
  let name: String?
  let dataArray: [User]

   enum Keys: String, CodingKey {
              case name
              case dataArray
   }          

   init(from decoder: Decoder) throws {
       let container = try decoder.container(keyedBy: Keys.self)
        name = try? container.decode(String.self, forKey: .name)
        dataArray =  (try? container.decode(User, forKey: . dataArray)) ?? []
    }
}

或者您可以创建一个包装器:

struct Data: Codable {
  let name: String?
  private let _dataArray: [User]?

  var dataArray : [User] {
      get {
        return   _dataArray ?? []
      }
   }

   enum Keys: String, CodingKey {
                case name
                case dataArray
   }
}