Swift:在 switch 语句中测试类类型 [英] Swift: Test class type in switch statement

问题描述

在 Swift 中，您可以使用is"检查对象的类类型.如何将其合并到开关"块中?

In Swift you can check the class type of an object using 'is'. How can I incorporate this into a 'switch' block?

我认为这是不可能的，所以我想知道解决这个问题的最佳方法是什么.

I think it's not possible, so I'm wondering what is the best way around this.

推荐答案

您绝对可以在 switch 块中使用 is.请参阅 Swift Programming Language 中的Type Casting for Any and AnyObject"(当然它不限于 Any).他们有一个广泛的例子:

You absolutely can use is in a switch block. See "Type Casting for Any and AnyObject" in the Swift Programming Language (though it's not limited to Any of course). They have an extensive example:

for thing in things {
    switch thing {
    case 0 as Int:
        println("zero as an Int")
    case 0 as Double:
        println("zero as a Double")
    case let someInt as Int:
        println("an integer value of (someInt)")
    case let someDouble as Double where someDouble > 0:
        println("a positive double value of (someDouble)")
// here it comes:
    case is Double:
        println("some other double value that I don't want to print")
    case let someString as String:
        println("a string value of "(someString)"")
    case let (x, y) as (Double, Double):
        println("an (x, y) point at (x), (y)")
    case let movie as Movie:
        println("a movie called '(movie.name)', dir. (movie.director)")
    default:
        println("something else")
    }
}

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