Swift 4 按值复制对象数组，其中包含数组

Question

我想了解 copy() 函数在 Swift 中的工作原理 4. 我有两个类的结构如下：

class Project {
    var id: Int
    var name: String
    var team: [Person]?

    init(id: Int, name: String, team: [Person]?) {
        self.id = id
        self.name = name
        self.team = team
    }
}

class Person {
    var id: Int
    var name: String
    var project: Project?

    init(id: Int, name: String, project: Project?) {
        self.id = id
        self.name = name
        self.project = project
    }
}

在我的程序中，我有一个项目数组，我想做的是通过以下方式在数组中创建值的副本：

// arrProjects is some array of projects.
let projectsCopy = arrProjects.map { [=12=].copy() } as! [Project]

为了实现这一点，我已经通过以下方式为类实现了 NSCopying 协议：

extension Project: NSCopying {
    public func copy(with zone: NSZone? = nil) -> Any {
        let teamCopy = self.team?.map { [=13=].copy() } as! [Person]?
        return Project(id: self.id, name: self.name, team: teamCopy)
    }
}

extension Person: NSCopying {
    public func copy(with zone: NSZone? = nil) -> Any {
        let projectCopy = self.project?.copy() as! Project?
        return Person(id: self.id, name: self.name, project: projectCopy)
    }
}

但是，当我运行代码和 arrProjects.map { [=16=].copy() } 运行s 时，应用程序冻结，就好像它在循环一样，并且 Thread 1: EXC_BAD_ACCESS (code=2, address=0x7ffee5a61ff8) 错误被抛出let teamCopy = self.team?.map { [=18=].copy() } as! [Person]?行。

知道我哪里出错了吗？

Answer 1

你不应该在 public func copy(with zone: NSZone? = nil) -> Any { 的定义中使用 copy() 您正在创建一个无限循环。

extension Project: NSCopying {
    public func copy(with zone: NSZone? = nil) -> Any {
        let copy = Project(id: self.id, name: self.name, team: self.team)
        return copy
    }
}

extension Person: NSCopying {
    public func copy(with zone: NSZone? = nil) -> Any {
        let copy = Person(id: self.id, name: self.name, project: self.project)
        return copy
    }
}

Swift 4 按值复制对象数组，其中包含数组

Swift 4 Copy an array of objects by value which have array inside

arrays

copy

nscopying

swift