Question

我知道如何使用switch语句在枚举案例中提取关联值：

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)")
}

但我想知道是否有办法使用元组提取相关值。

我试过

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

正如所料，它没有用。有没有办法将枚举案例的相关值转换为元组？还是不可能？

Answer 1

您可以使用与if case let匹配的模式来提取一个特定枚举值的关联值：

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)
}

Answer 2

您可以在此方案中使用元组

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)")
}


typealias tupleBarcode = (one:Int, two:Int,three: Int, three:Int)

switch productBarcode {
case  let .upc(tupleBarcode):
    print("upc: \(tupleBarcode)")
case .quCode(let productCode):
    print("quCode \(productCode)")
}

upc：（8,10,15,2）

upc：（8,10,15,2）

将枚举案例的关联值提取到元组中

2 个答案: