Apple Grand Central Dispatch (GCD) in Swift

parallel.swift

import Foundation

func async(block: () -> (), priority: Int = DISPATCH_QUEUE_PRIORITY_DEFAULT) {
  dispatch_async(dispatch_get_global_queue(priority, 0), block)
}

func par(count: UInt, block: (UInt) -> (), priority: Int = DISPATCH_QUEUE_PRIORITY_DEFAULT) {
  dispatch_apply(count, dispatch_get_global_queue(priority, 0), block)
}

async {
  println("foo")
}

par(20) {
  println("\($0)")
}

sleep(1)
println("Got it!")

Any idea why par(20) isn't producing a list of values between 0 and 19?