Void is a type!

Voidstar.playground.swift

// This playground was built for Xcode 6.2 and is compatible with Xcode 6.3b3.
// The contents are true to the best of my knowledge and are not an April Fools joke.
// However, if you -actually- implement some of this stuff...

// In Swift, Void is a typealias for an empty tuple
// Cmd-Click the keyword Void to see this typealias
func example1() {
    let myVoid: Void = ()
    println("\(myVoid)")
}
example1()

// Remember, a tuple can be decomposed
// See 'The Swift Programming Language', pg 55
func example2() {
    let myTuple = ("hello", "world")
    let (word1, word2) = myTuple
    println("\(word1), \(word2)")
}
example2()

// You can also decompose the results of a tuple-returning function call directly
func example3() {
    func returnsTuple() -> (String, String) {
        return ("hello", "world")
    }
    let (word1, word2) = returnsTuple()
    println("\(word1), \(word2)")
}
example3()

// Since Void is a type, you can assign the results of a Void-returning function call
func example4() {
    func returnVoid() -> Void {}
    let myVoid: Void = returnVoid()
    println("\(myVoid)")
}
example4()

// Keep in mind that since the return type of a function is implicitly Void, you can assign a function call even without
// an explicit return type
func example5() {
    func returnVoid() {}
    let () = returnVoid()
}
example5()

// You can also use tuple-decomposition syntax, assigning it to an 0-length list of variables
func example6() {
    func returnVoid() {}
    let () = returnVoid()
}
example6()

// This explains all kinds of errors you see regarding type '()' when you're not dealing with tuples
// Uncomment the following function to see some of these errors
//func example7() {
//    func attemptToReturnNonZeroLengthTuple() {
//        // error: type '()' does not conform to protocol 'IntegerLiteralConvertible'
//        return (1)
//    }
//    func attemptToReturnConcreteObject() {
//        // error: 'String' is not convertible to '()'
//        return "hello world"
//    }
//}
//example7()