有什么方法可以快速迭代元组? [英] Any way to iterate a tuple in swift?

问题描述

我很好奇如何快速使用元组进行 for 循环.

I am curious how to do a for loop with a tuple in swift.

我知道要访问每个成员，您可以使用索引号使用点表示法

I know that to access each member you can use dot notation using the index number

var tupleList = ("A",2.9,3,8,5,6,7,8,9)

for each in tupleList {
    println(each)
}

//错误:类型不符合协议序列

//Error: Type does not conform to protocol sequence

推荐答案

是的，你可以！

func iterate<C,R>(t:C, block:(String,Any)->R) {
    let mirror = reflect(t)
    for i in 0..<mirror.count {
        block(mirror[i].0, mirror[i].1.value)
    }
}

瞧！

let tuple = ((false, true), 42, 42.195, "42.195km")
iterate(tuple) { println("\($0) => \($1)") }
iterate(tuple.0){ println("\($0) => \($1)")}
iterate(tuple.0.0) { println("\($0) => \($1)")} // no-op

注意最后一个不是元组，所以什么也不会发生(尽管它是一个 1 元组或单个"，其内容可以被访问 .0, reflect(it).count 为 0).

Note the last one is not a tuple so nothing happens (though it is a 1-tuple or "Single" which content can be accessed .0, reflect(it).count is 0).

有趣的是 iterate() 甚至可以迭代其他类型的集合.

What's interesting is that iterate() can iterate even other types of collection.

iterate([0,1])              { println("\($0) => \($1)") }
iterate(["zero":0,"one":1]) { println("\($0) => \($1)") }

该集合包括 class 和 struct！

struct Point { var x = 0.0, y = 0.0 }
class  Rect  { var tl = Point(), br = Point() }
iterate(Point()) { println("\($0) => \($1)") }
iterate(Rect())  { println("\($0) => \($1)") }

警告:作为块的第二个参数传递的值是 Any 类型.您必须将其转换回原始类型的值.

Caveat: the value passed as the 2nd argument of the block is type Any. You have to cast it back to the values with original type.

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