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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。
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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