Elapsed time

November 12, 2022

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Below are two 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 both examples is approximately 4 seconds.

import Foundation

// Example 1
// ---------------------------------------------------------------------------

let tic = DispatchTime.now().uptimeNanoseconds

sleep(4)

let toc = DispatchTime.now().uptimeNanoseconds

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

// Example 2
// ---------------------------------------------------------------------------

let tic2 = CFAbsoluteTimeGetCurrent()

sleep(4)

let toc2 = CFAbsoluteTimeGetCurrent()

print("Elapsed time is \(toc2 - tic2) seconds")

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

$ swift elapsedtime.swift
Elapsed time is 4 seconds
Elapsed time is 4.000399947166443 seconds