classswiftswitch-statement

Swift: Test class type in switch statement


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

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


Solution

  • 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")
        }
    }