Swift-如何获取数组过滤项的索引 [英] Swift - How to get indexes of filtered items of array

问题描述

let items: [String] = ["A", "B", "A", "C", "A", "D"]

items.whatFunction("A") // -> [0, 2, 4]
items.whatFunction("B") // -> [1]

Swift 3是否支持whatFunction(_: Element)之类的功能?

Does Swift 3 support a function like whatFunction(_: Element)?

如果没有，最有效的逻辑是什么?

If not, what is the most efficient logic?

推荐答案

您可以为数组创建自己的扩展名.

You can create your own extension for arrays.

extension Array where Element: Equatable {
    func indexes(of element: Element) -> [Int] {
        return self.enumerated().filter({ element == $0.element }).map({ $0.offset })
    }
}

您可以这样简单地称呼它

You can simply call it like this

items.indexes(of: "A") // [0, 2, 4]
items.indexes(of: "B") // [1]

这篇关于Swift-如何获取数组过滤项的索引的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！