Time code execution in Swift

timeIt.swift

import CoreFoundation

func timeIt(m: () -> ()) -> (Double, Int) {
    let startTime = CFAbsoluteTimeGetCurrent()
    var numberOfRuns = 0
    while true {
        m()
        numberOfRuns += 1
        let elapsed = CFAbsoluteTimeGetCurrent() - startTime
        if elapsed > 0.5 { // we run the function up to 0.5 seconds, assuming here that we want to sample functions that are pretty fast 
            return (Double(numberOfRuns) / elapsed, numberOfRuns)
        }
    }
}

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

let (opsPerSecond, samples) = timeIt({
  for i in 0..<N {
    B[i] = Float(i)
  }
})

print("\(opsPerSecond) ops/second, \(samples) samples")