Time code execution in Swift

timeIt.swift

func timeIt(function: ()->()) -> Double {
  var startTime = NSDate()
  function()
  return -startTime.timeIntervalSinceNow
}

let N = 800
var B = [Float](count: N, repeatedValue: 0)

elapsed = timeIt({
  for i in 0..<N {
    B[i] = Float(i)
  }
})