检查自定义对象数组是否包含特定自定义对象 [英] Checking if an array of custom objects contain a specific custom object

问题描述

说我有一个非常简单的Person 类

say i have a very simple Person class

class Person {
    var name:String
    init(name:String) {
        self.name = name
    }
}

并且我希望将此类 Person 的集合存储在一个属性中，该属性是一个 People 类的 Person 类型的数组

and i wish to store a collections of such Persons in a property, which is an array with type Person, of a People class

class People {
    var list:[Person] = []
}

也许我是这样实现的

var alex = Person(name:"Alex")
var people = People()
people.list.append(alex)

问题:我如何检查 people.list 是否包含实例 alex?

QUESTION: how do i check if people.list contains the instance alex, please?

我的简单尝试，我希望返回 true

my simple attempt, which i was hoping to return true

people.list.contains(alex)

调用错误无法将'Person'类型的值转换为预期的参数类型'@noescape (Person) throws -> Bool'"

推荐答案

有两个contains函数:

extension SequenceType where Generator.Element : Equatable {
    /// Return `true` iff `element` is in `self`.
    @warn_unused_result
    public func contains(element: Self.Generator.Element) -> Bool
}

extension SequenceType {
    /// Return `true` iff an element in `self` satisfies `predicate`.
    @warn_unused_result
    public func contains(@noescape predicate: (Self.Generator.Element) throws -> Bool) rethrows -> Bool
}

编译器抱怨是因为编译器知道Person 不是Equatable，因此contains 需要有一个谓词 但 alex 不是谓词.

The compiler is complaining because the compiler knows that Person is not Equatable and thus contains needs to have a predicate but alex is not a predicate.

如果您数组中的人是 Equatable(他们不是)，那么您可以使用:

If the people in your array are Equatable (they aren't) then you could use:

person.list.contains(alex)

由于它们不相等，您可以使用第二个 contains 函数:

Since they aren't equatable, you could use the second contains function with:

person.list.contains { $0.name == alex.name }

或者，正如 Martin R 指出的，基于身份":

or, as Martin R points out, based on 'identity' with:

person.list.contains { $0 === alex }

或者您可以使 Person 成为 Equatable(基于 name 或身份).

or you could make Person be Equatable (based on either name or identity).

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