使用索引将 Swift 数组转换为字典 [英] Convert Swift Array to Dictionary with indexes

问题描述

我使用的是 Xcode 6.4

I'm using Xcode 6.4

我有一个 UIView 数组，我想转换为带有键 "v0", "v1"... 的字典.像这样:

I have an array of UIViews and I want to convert to a Dictionary with keys "v0", "v1".... Like so:

var dict = [String:UIView]()
for (index, view) in enumerate(views) {
  dict["v(index)"] = view
}
dict //=> ["v0": <view0>, "v1": <view1> ...]

这行得通，但我正在尝试以更实用的风格来实现.我想我必须创建 dict 变量让我很困扰.我喜欢像这样使用 enumerate() 和 reduce() :

This works, but I'm trying to do this in a more functional style. I guess it bothers me that I have to create the dict variable. I would love to use enumerate() and reduce() like so:

reduce(enumerate(views), [String:UIView]()) { dict, enumeration in
  dict["v(enumeration.index)"] = enumeration.element // <- error here
  return dict
}

这感觉更好，但我收到错误:无法将UIView"类型的值分配给UIView"类型的值?>UIView(即:[String] -> [String:String])我得到同样的错误.

This feels nicer, but I'm getting the error: Cannot assign a value of type 'UIView' to a value of type 'UIView?' I have tried this with objects other an UIView (ie: [String] -> [String:String]) and I get the same error.

有什么清理它的建议吗?

Any suggestions for cleaning this up?

推荐答案

试试这个:

reduce(enumerate(a), [String:UIView]()) { (var dict, enumeration) in
    dict["(enumeration.index)"] = enumeration.element
    return dict
}

Xcode 8 • Swift 2.3

extension Array where Element: AnyObject {
    var indexedDictionary: [String:Element] {
        var result: [String:Element] = [:]
        for (index, element) in enumerate() {
            result[String(index)] = element
        }
        return result
    }
}

Xcode 8 • Swift 3.0

extension Array  {
    var indexedDictionary: [String: Element] {
        var result: [String: Element] = [:]
        enumerated().forEach({ result[String($0.offset)] = $0.element })
        return result
    }
}

Xcode 9 - 10 • Swift 4.0 - 4.2

使用 Swift 4 reduce(into:) 方法:

Using Swift 4 reduce(into:) method:

extension Collection  {
    var indexedDictionary: [String: Element] {
        return enumerated().reduce(into: [:]) { $0[String($1.offset)] = $1.element }
    }
}

<小时>

使用 Swift 4 Dictionary(uniqueKeysWithValues:) 初始化器并从枚举集合中传递一个新数组:

---

Using Swift 4 Dictionary(uniqueKeysWithValues:) initializer and passing a new array from the enumerated collection:

extension Collection {
    var indexedDictionary: [String: Element] {
        return Dictionary(uniqueKeysWithValues: enumerated().map{(String($0),$1)})
    }
}

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