我如何做 indexOfObject 或适当的 containsObject [英] How do I do indexOfObject or a proper containsObject

问题描述

使用数组:如何做 indexOfObject 或适当的 containsObject?

With an array: How do I do indexOfObject or a proper containsObject?

我的意思是我知道我可以将 Array 桥接到 NSArray 并在那里完成 ^^
但必须有一种原生"的方式来做到这一点

I mean I know I could just bridge the Array to NSArray and do it there ^^
But there must be a 'native' way of doing this

附言对于 containsObject 我想我也可以过滤数组但是对于 indexOf?

P.S. for the containsObject I guess I could filter the array too but for indexOf?

推荐答案

您可以使用内置的 find，从而避免桥接到 Objective-C — 但前提是您的元素类型是 Equatable.(如果它不是 Equatable，您可以使用比较函数和扩展来实现.)

You can use the built-in find, and thus avoid bridging to Objective-C — but only if your element type is Equatable. (If it isn't Equatable, you can make it so with a comparison function and an extension.)

示例:

func == (lhs:Piece,rhs:Piece) -> Bool {
    return lhs.val == rhs.val
}

class Piece:Equatable,Printable {
    var val : Int
    var description : String { return String(val) }
    init (_ v:Int) {
        val = v
    }
}

现在你可以调用 find(arr,p) 其中 arr 是一个 Array 和 p> 是一个 Piece.

Now you can call find(arr,p) where arr is an Array<Piece> and p is a Piece.

一旦你有了它，你就可以基于它开发实用程序.例如，这里有一个全局函数，用于从数组中删除一个对象，而无需桥接到 Objective-C:

Once you have this, you can develop utilities based on it. For example, here's a global function to remove an object from an array without bridging to Objective-C:

func removeObject<T:Equatable>(inout arr:Array<T>, object:T) -> T? {
    if let found = find(arr,object) {
        return arr.removeAtIndex(found)
    }
    return nil
}

然后像这样测试:

var arr = [Piece(1), Piece(2), Piece(3)]
removeObject(&arr,Piece(2))
println(arr)

<小时>

您也可以对 NSObject 子类执行此操作.示例:

---

You can do this for NSObject subclasses too. Example:

func == (v1:UIView, v2:UIView) -> Bool {
    return v1.isEqual(v2)
}
extension UIView : Equatable {}

现在您可以在 UIView 数组上调用 find.但是，这有点麻烦，必须为每个您希望能够在该类的 Array 上使用 find 的类执行此操作.我已经向 Apple 提交了一份增强请求，要求将所有 NSObject 子类都视为 Equatable，并且 == 应该依靠 isEqual: 自动.

Now you can call find on an Array of UIView. It's sort of a pain in the butt, though, having to do this for every single class where you want to be able to use find on an Array of that class. I have filed an enhancement request with Apple requesting that all NSObject subclasses be considered Equatable and that == should fall back on isEqual: automatically.

编辑 从 Seed 3 开始，对于 UIView 和其他 NSObject 类是自动的.所以 find 现在只对他们有用.

EDIT Starting in Seed 3, this is automatic for UIView and other NSObject classes. So find now just works for them.

EDIT 2 从 Swift 2.0 开始，indexOf 将作为方法存在:

EDIT 2 Starting in Swift 2.0, indexOf will exist as a method:

let s = ["Manny", "Moe", "Jack"]
let ix = s.indexOf("Moe") // 1

或者，它需要一个返回 Bool 的函数:

Alternatively, it takes a function that returns Bool:

let ix2 = s.indexOf {$0.hasPrefix("J")} // 2

同样，这仅适用于 Equatable 的集合，因为显然你无法在大海捞针中找到针，除非你有办法识别针.

Again, this works only on collections of Equatable, since obviously you cannot locate a needle in a haystack unless you have a way of identifying a needle when you come to it.

EDIT 3 Swift 2.0 还引入了协议扩展.这意味着我可以将我的全局函数 removeObject 重写为一个方法！

EDIT 3 Swift 2.0 also introduces protocol extensions. This means I can rewrite my global function removeObject as a method!

例如:

extension RangeReplaceableCollectionType where Generator.Element : Equatable {
    mutating func removeObject(object:Self.Generator.Element) {
        if let found = self.indexOf(object) {
            self.removeAtIndex(found)
        }
    }
}

既然Array采用了RangeReplaceableCollectionType，现在可以这样写代码了:

Since Array adopts RangeReplaceableCollectionType, now I can write code like this:

var arr = [Piece(1), Piece(2), Piece(3)]
arr.removeObject(Piece(2))

哦，快乐的一天！

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