测试速记，如果在斯威夫特数组存在的对象？ [英] Shorthand to test if an object exists in an array for Swift?

问题描述

目前，我有对象，像这样的数组：

Currently, I have an array of objects like this:

var myArr = [
  MyObject(name: "Abc", description: "Lorem ipsum 1."),
  MyObject(name: "Def", description: "Lorem ipsum 2."),
  MyObject(name: "Xyz", description: "Lorem ipsum 3.")
]

我测试某个对象继续像在此之前存在：

I am testing if an object exists before proceeding like this:

let item = myArr.filter { $0.name == "Def" }.first
if item != nil {
  // Do something...
}

但我在寻找一个较短的方式做到这一点，因为我这样做了很多。我想这样做，但它是无效的：

But I'm looking for a shorter way to do this since I am doing this a lot. I'd like to do something like this but it is invalid:

if myArr.contains { $0.name == "Def" } {
  // Do something...
}

有没有语法速记我丢失或更好的方式来做到这一点？

Is there any shorthand syntax I'm missing or a better way to do this?

推荐答案

为什么不使用内置的包含（）功能？它有两种形式

Why not use the built-in contains() function? It comes in two flavors

func contains<S : SequenceType, L : BooleanType>(seq: S, predicate: @noescape (S.Generator.Element) -> L) -> Bool
func contains<S : SequenceType where S.Generator.Element : Equatable>(seq: S, x: S.Generator.Element) -> Bool

和第一个需要花费predicate作为参数。<​​/ P>

and the first one takes a predicate as argument.

if contains(myArr, { $0.name == "Def" }) {
    println("yes")
}

更新：由于斯威夫特2，包括全球包含（）函数有
被取代的的协议扩展方法的：

extension SequenceType where Generator.Element : Equatable {
    func contains(element: Self.Generator.Element) -> Bool
}

extension SequenceType {
    func contains(@noescape predicate: (Self.Generator.Element) -> Bool) -> Bool
}

和所述第一（predicate为主）之一被用作

and the first (predicate-based) one is used as:

if myArr.contains( { $0.name == "Def" }) {
    print("yes")
}

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