数组中的最后一个元素将覆盖之前的所有元素

Question

我试图将JSON中的数据保存到数组中，但最后一项覆盖了前面的值。我有一个用于存储学生信息的学生类和一个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)"
    }
}

学生班

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())
                }
            }
        }
    }
}

我在技能数组上循环，并将其附加到我的学生技能数组，并打印最后一个附加的值，正确的值被打印出来。

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())
 }

在for循环中，从上述打印输出

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

当我在上面的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，我如何解决这个问题？




Answer 1

你总是在数组中附加相同的技能。每次您在循环中修改它。你应该每次都创建新的技能。

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

如果Skill是一个值类型（struct），但它是一个引用类型（class），并且指向同一个对象，那么您的方法就会起作用。