arrays - 数组中的最后一个元素覆盖所有先前的元素

Question

我正在尝试将 JSON 中的数据保存到数组中，但最后一项会覆盖以前的值。我有一个用于存储学生信息的学生类和用于存储学生技能的技能类。

public class Skill {
    public var id : Int = 0
    public var name : String = ""
    public var level : Double = 0.0

    func description() -> String {
        return "ID: \(id), " +
            "name: \(name), " +
        "level: \(level)"
    }
}

学生类

public class Student {

    public var studentSkills = Array<Skill>()


    func setCursusUsers(data: [[String: AnyObject]]) {
        for item in data {
            let skills = Skill()
            if let resData = item["skills"]  {
                let stu_data = resData as! [[String: AnyObject]]
                for skill_item in stu_data {
                    skills.id = skill_item["id"] as? Int ?? 0
                    skills.level = skill_item["level"] as? Double ?? 0.0
                    skills.name = skill_item["name"] as? String ?? ""
                    studentSkills.append(skills)
                    print(studentSkills[studentSkills.count - 1].description())
                }
                for skill in studentSkills {
                    print(skill.description())
                }
            }
        }
    }
}

我循环遍历技能数组并将其附加到我的 studentSkills 数组中，并打印最后附加的值，并打印出正确的值。

for skill_item in stu_data {
    skills.id = skill_item["id"] as? Int ?? 0
    skills.level = skill_item["level"] as? Double ?? 0.0
    skills.name = skill_item["name"] as? String ?? ""
    studentSkills.append(skills)
    print(studentSkills[studentSkills.count - 1].description())
 }

上面 for 循环内 print 的输出

ID: 16, name: Company experience, level: 11.34
ID: 4,  name: Unix, level: 7.4
ID: 17, name: Object-oriented programming, level: 4.59
ID: 3,  name: Rigor, level: 3.24
ID: 7,  name: Group & interpersonal, level: 3.02
ID: 2,  name: Imperative programming, level: 2.98
ID: 6,  name: Web, level: 2.32
ID: 13, name: Organization, level: 1.8
ID: 14, name: Adaptation & creativity, level: 1.14
ID: 5,  name: Graphics, level: 1.12
ID: 10, name: Network & system administration, level: 0.98
ID: 12, name: DB & Data, level: 0.87
ID: 15, name: Technology integration, level: 0.82
ID: 1,  name: Algorithms & AI, level: 0.76
ID: 11, name: Security, level: 0.45

当我在上述 for 循环之外运行以下代码时

for skill in studentSkills {
    print(skill.description())
}

我得到以下输出

ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 11, name: Security, level: 0.45
ID: 7, name: Group & interpersonal, level: 0.21
ID: 7, name: Group & interpersonal, level: 0.21
ID: 7, name: Group & interpersonal, level: 0.21
ID: 7, name: Group & interpersonal, level: 0.21

这是我的 JSON 的结构

"cursus_users" : [
  {
    "skills" : [
      ...,
      ...,
      ...,
      ...,
      ...,
      ...,
      ...,
      ...,
      {
        "id" : 11,
        "name" : "Security",
        "level" : 0.45
      }
    ],
    ...
  },
  {
    "skills" : [
      ...,
      ...,
      ...,
      {
        "id" : 7,
        "name" : "Group & interpersonal",
        "level" : 0.21
      }
    ],
    ...
  }
]

技能数组的最后一个元素覆盖了前面的元素，我该如何解决这个问题？

Answer 1

您总是将相同的技能附加到数组中。每次在 for 循环中修改它。您应该每次都创建新的技能。

for skill_item in stu_data {
     let skills = Skill()
     ...
}

如果 Skill 是值类型 (struct)，但它是引用类型 (class) 并指向同一个对象。