Swift方法执行耗时测量

gistfile1.txt

func measure(block: () -> Void) -> Double {
    let start = DispatchTime.now()
    block()
    let end = DispatchTime.now()
    let nanoTime = end.uptimeNanoseconds - start.uptimeNanoseconds // <<<<< Difference in nano seconds (UInt64)
    let timeInterval = Double(nanoTime) / 1_000_000_000
    return timeInterval
}