Gavin Wiggins

Measure Elapsed Time of Swift Code

Published on June 24, 2024
Tagged with swift

The functions shown below are examples of measuring elapsed time in Swift. The sleep function is used to delay the code execution for 4 seconds. Consequently, the elapsed time for each example is approximately 4 seconds.

import Foundation

func exampleOne() {
    let tic = DispatchTime.now().uptimeNanoseconds
    sleep(4)
    let toc = DispatchTime.now().uptimeNanoseconds

    print("Elapsed time is \((toc - tic) / 1_000_000_000) seconds")
}

func exampleTwo() {
    let tic = CFAbsoluteTimeGetCurrent()
    sleep(4)
    let toc = CFAbsoluteTimeGetCurrent()

    print("Elapsed time is \(toc - tic) seconds")
}

func exampleThree() {
    let tic = Date.now
    sleep(4)
    let toc = tic.timeIntervalSinceNow.magnitude

    print("Elapsed time is \(toc) seconds")
}

func exampleFour() {
    let clock = ContinuousClock()
    let result = clock.measure {
        sleep(4)
    }

    print("Elapsed time is \(result)")
}

exampleOne()
exampleTwo()
exampleThree()
exampleFour()

Running the above code in a file named elapsedtime.swift gives the following output:

$ swiftc elapsedtime.swift; ./elapsedtime

Elapsed time is 4 seconds
Elapsed time is 4.005115985870361 seconds
Elapsed time is 4.005129098892212 seconds
Elapsed time is 4.003226656 seconds

All of the code in this post is available on GitHub at swift-macos/swift-scripts/elapsedtime.swift.