如何对Swift代码执行进行基准测试？

Question

let date_start = NSDate()

// Code to be executed 

println("\(-date_start.timeIntervalSinceNow)")

Answer 1

如果您只是想为一段代码提供一个独立的计时函数，我使用以下Swift帮助函数：

func printTimeElapsedWhenRunningCode(title:String, operation:()->()) {
    let startTime = CFAbsoluteTimeGetCurrent()
    operation()
    let timeElapsed = CFAbsoluteTimeGetCurrent() - startTime
    print("Time elapsed for \(title): \(timeElapsed) s.")
}

func timeElapsedInSecondsWhenRunningCode(operation: ()->()) -> Double {
    let startTime = CFAbsoluteTimeGetCurrent()
    operation()
    let timeElapsed = CFAbsoluteTimeGetCurrent() - startTime
    return Double(timeElapsed)
}

前者将注销给定代码段所需的时间，后者将其作为浮点返回。作为第一种变体的示例：

printTimeElapsedWhenRunningCode(title:"map()") {
    let resultArray1 = randoms.map { pow(sin(CGFloat($0)), 10.0) }
}

将注销如下内容：