Using ".." with for loop

Question

There is a code snippet in the swift book provided by Apple. I typed it in xcode playground but it shows "Operator is not a known binary operator" and "Use of unresolved identifier" errors. The code is:

According to the book, ".." operator can be used with for loop to make a range that omits its upper value. But it displays error. Changing ".." to "..." operator seems to fix the error. But why does not ".." work?

Answer 1

You have an out of date version of the swift book.

Here you go. The current version of the half-closed range is 0..<3 not 0..3 https://developer.apple.com/library/ios/documentation/swift/conceptual/Swift_Programming_Language/BasicOperators.html

Answer 2

Things are now different in Swift 2. Here's how to do it now in Xcode 7 (the original question shows highly in a google search for this particular problem):

for i in 1 ..< Process.argc {
    let index = Int(i);

    if let arg = String.fromCString(Process.unsafeArgv[index]) {
        switch arg {
        case "-whatever":
            // do something

        default:
            break
        }
    }
}