展平 [Any] 数组 Swift [英] Flatten [Any] Array Swift

问题描述

使用 this 堆栈溢出问题我有以下代码.

Using this Stack Overflow question I have the following code.

let numbers = [1,[2,3]] as [Any]
var flattened = numbers.flatMap { $0 }
print(flattened) // [1, [2, 3]]

与其将扁平化设置为 [1, [2, 3]] 我希望它是 [1, 2, 3].

Instead of flattened being set to [1, [2, 3]] I want it to be [1, 2, 3].

在 Swift 中实现这一目标的最简单/最简洁的方法是什么?

What is the easiest/cleanest way to achieve this in Swift?

推荐答案

extension Collection where Element == Any {
    var joined: [Any] { flatMap { ($0 as? [Any])?.joined ?? [$0] } }
    func flatMapped<T>(_ type: T.Type? = nil) -> [T] { joined.compactMap { $0 as? T } }
}

---

let objects: [Any] = [1,[2,3],"a",["b",["c","d"]]]
let joined = objects.joined()   // [1, 2, 3, "a", "b", "c", "d"]

let integers = objects.flatMapped(Int.self)  // [1, 2, 3]
// setting the type explicitly
let integers2: [Int] = objects.flatMapped()        // [1, 2, 3]
// or casting
let strings = objects.flatMapped() as [String]     // ["a", "b", "c", "d"]

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