将枚举案例的关联值提取到元组中 [英] Extract associated value of enum case into a tuple

问题描述

我知道如何使用switch语句在枚举案例中提取关联值：

I know how to extract associated values in enum cases using switch statement:

enum Barcode {
    case upc(Int, Int, Int, Int)
    case quCode(String)
}
var productBarcode = Barcode.upc(8, 10, 15, 2)

switch productBarcode {
case  let .upc(one, two, three, four):
    print("upc: \(one, two, three, four)")
case .quCode(let productCode):
    print("quCode \(productCode)")
}

但是我想知道是否存在一种使用元组提取关联值的方法。

But I was wondering if there is a way to extract associated value using tuples.

我尝试了

let (first, second, third, fourth) = productBarcode

<如预期的那样，它没有用。有没有办法将枚举案例的关联值转换为元组？还是不可能？

As expected, it did not work. Is there a way to turn associated value of enum cases into a tuple? or it is not possible?

推荐答案

如果情况允许，您可以将模式匹配与一起使用提取一个特定枚举值的
关联值：

You can use pattern matching with if case let to extract the associated value of one specific enumeration value:

if case let Barcode.upc(first, second, third, fourth) = productBarcode {
    print((first, second, third, fourth)) // (8, 10, 15, 2)
}

或

if case let Barcode.upc(tuple) = productBarcode {
    print(tuple) // (8, 10, 15, 2)
}

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