swift - 多个选项的快速解包

Question

我认为这是可能的，但似乎无法让它发挥作用。我敢肯定我只是愚蠢。我试图以以下形式输出格式化地址

"one, two, three"

来自一组可选组件（一个、两个、三个）。如果 "two" 为 nil，则输出为

"one, three"

let one: String?
let two: String?
let three: String?

one = "one"
two = nil
three = "three"

if let one = one,
        two = two,
        three = three {
     print("\(one),\(two),\(three)")
}

Answer 1

我不知道你为什么需要这个，但接受它=）

if let _ = one ?? two ?? three {
    print("\(one),\(two),\(three)")
}

Answer 2

如果您尝试将非nil值打印为逗号分隔的列表，那么我认为@MartinR 的使用建议flatMap()是最好的：

let one: String?
let two: String?
let three: String?

one = "one"
two = nil
three = "three"

let nonNils = [one, two, three].flatMap { $0 }
if !nonNils.isEmpty {
    print(nonNils.joinWithSeparator(","))
}

输出：

one,three