Exhaustive condition of switch case in Swift

Swift only truly verifies that a switch block is exhaustive when working with enum types. Even a switching on Bool requires a default block in addition to true and false:

var b = true
switch b {
case true:  println("true")
case false: println("false")
}
// error: switch must be exhaustive, consider adding a default clause

With an enum, however, the compiler is happy to only look at the two cases:

enum MyBool {
    case True
    case False
}

var b = MyBool.True
switch b {
case .True:  println("true")
case .False: println("false")
}

If you need to include a default block for the compiler’s sake but don’t have anything for it to do, the break keyword comes in handy:

var b = true
switch b {
case true:  println("true")
case false: println("false")
default: break
}