swift - 如何在这个 Swift for-in 示例中打印两个键值对

Question

此示例来自 Apple 的“A Swift Guide”部分，用于演示 for-in。

super 新手的问题，但它为什么不打印 type 变量呢？跟作用域有关系吗？

let interestingNumbers = [
    "Prime": [2, 3, 5, 7, 11, 13],
    "Fibonacci": [1, 1, 2, 3, 5, 8],
    "Square": [1, 4, 9, 16, 25],
]
var largest = 0
var type: String
for (kind, numbers) in interestingNumbers {
    for number in numbers {
        if number > largest {
            largest = number
            type = kind
        }
    }
}
largest
type

Answer 1

首先像这样将type初始化为一个空字符串:

var type: String = ""