arrays - Swift switch case 使用数组内容，语法？

Question

Apple 的 Swift Book 有一个使用元音作为大小写的开关示例。

问题。 除了这个元音列表，是否可以使用包含这些内容的数组？如果是这样，这样做的语法是什么？

---

~ 来自 Apple Swift Book ~

The following example removes all vowels and spaces from a lowercase string to create a cryptic puzzle phrase:

let puzzleInput = "great minds think alike"
var puzzleOutput = ""
for character in puzzleInput.characters {
    switch character {
    case "a", "e", "i", "o", "u", " ":
        continue
    default:
        puzzleOutput.append(character)
    }
}
print(puzzleOutput)
// Prints "grtmndsthnklk"

Answer 1

是的:

let puzzleInput = "great minds think alike"
var puzzleOutput = ""
let vowels: [Character] = ["a", "e", "i", "o", "u", " "]

for character in puzzleInput.characters {
    switch character {
    case _ where vowels.contains(character):
        continue
    default:
        puzzleOutput.append(character)
    }
}

Swift 中的

case 匹配依赖于模式匹配运算符 (~=)。如果为它定义一个新的重载，则可以进一步缩短代码:

func ~=<T: Equatable>(pattern: [T], value: T) -> Bool {
    return pattern.contains(value)
}

for character in puzzleInput.characters {
    switch character {
    case vowels:
        continue
    default:
        puzzleOutput.append(character)
    }
}