如何创建一组自定义对象 (Swift)？

Question

对于我的 iOS 应用程序，我有一个类似

的模型

class Person {
    var Id: Int
    var Name: String

    init(id: Int, name: String?) {
        self.Id = id
        self.Name = name ?? ""
    }
}

然后稍后在我的 ViewController 中，当我从服务器加载数据时，我将一些人添加到数组中

class ViewController: UIViewController {
    var people:[Person] = []

    override func viewDidLoad() {
        self.loadPeople()
    }

    func loadPeople() {
        // This data will be coming from a server request
        // so is just sample. It could have users which 
        // already exist in the people array

        self.people.append(Person(id: "1", name: "Josh"))
        self.people.append(Person(id: "2", name: "Ben"))
        self.people.append(Person(id: "3", name: "Adam"))
    }
}

我现在要做的是将 people 数组转换为 Set<Person>，这样它就不会添加重复项。这可以做还是我需要改变我的逻辑？

Answer 1

要制作 Person 集，您需要使其符合 Equatable 和 Hashable 协议：

class Person: Equatable, Hashable {
    var Id: Int
    var Name: String

    init(id: Int, name: String?) {
        self.Id = id
        self.Name = name ?? ""
    }

    var hashValue: Int {
        get {
            return Id.hashValue << 15 + Name.hashValue
        }
    }
}

func ==(lhs: Person, rhs: Person) -> Bool {
    return lhs.Id == rhs.Id && lhs.Name == rhs.Name
}

那么你可以使用这样一组人：

var set = Set<Person>()
set.insert(Person(id: 1, name: "name"))

Answer 2

在 Swift 2.0 中，Hashable 和 Equitable 是 NSObject 的一部分。您需要做的就是为感兴趣的属性覆盖 "isEqual" 和 "var hash:"。在这种情况下："Id"，Set 将排除具有相同 ID 的 Person-objects。

    class Person: NSObject {
        var Id: Int
        var Name: String

        init(id: Int, name: String?) {
            self.Id = id
            self.Name = name ?? ""
        }

        override var hash: Int {
        return Id.hashValue
   }

        override func isEqual(object: AnyObject?) -> Bool {
            guard let rhs = object as? Person else {
                return false
            }
            let lhs = self

            return lhs.Id == rhs.Id
        }


    }

          func mergeArrays(){
       let person1 = Person(id: 1, name: "Tom")
       let person2 = Person (id: 2, name: "John")
       let person3 = Person(id: 3, name: "Adam")


       let downloadedPeople  = [person1,person2] //[{NSObject, Id 1, Name "Tom"}, {NSObject, Id 2, Name "John"}] 

       let peopleStoredLocally = [person1,person3] //[{NSObject, Id 1, Name "Tom"}, {NSObject, Id 3, Name "Adam"}]

       let downloadedPeopleSet = Set(downloadedPeople) //{{NSObject, Id 2, Name "John"}, {NSObject, Id 1, Name "Tom"}}


       let mergedSet = downloadedPeopleSet.union(peopleStoredLocally) //{{NSObject, Id 2, Name "John"}, {NSObject, Id 3, Name "Adam"}, {NSObject, Id 1, Name "Tom"}}


       let mergedArray = Array(mergedSet)//[{NSObject, Id 2, Name "John"}, {NSObject, Id 3, Name "Adam"}, {NSObject, Id 1, Name "Tom"}]

    }

Answer 3

更新

使用 hashValue 时的弃用警告：

'Hashable.hashValue' is deprecated as a protocol requirement; conform type 'Person' to 'Hashable' by implementing 'hash(into:)' instead

以对象 Person 为例，现在的实现是：

class Person: Equatable, Hashable {

    let id: Int
    let countryId: Int
    var name: String
    
    init(id: Int, countryId: Int, name: String) {
        self.id = id
        self.countryId = countryId
        self.name = name
    }
    
    func hash(into hasher: inout Hasher) {
        hasher.combine(id)
        hasher.combine(countryId)
    }
    
    static func == (lhs: Person, rhs: Person) -> Bool {
        return lhs.id == rhs.id &&  lhs.countryId == rhs.countryId
    }
    
}

注意：根据文档，用于散列的组件必须与您的类型的 == 运算符实现中比较的组件相同。

如何创建一组自定义对象 (Swift)？

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