Measuring Time Accurately in Swift for Comparison Across Devices

Question

I need to be able to record reaction time, from when the screen loads or the question label refreshes until the user taps a number button. I\'m not finding documentation fro

Answer 1

You can use NSTimeInterval to measure time (much better than a timer). You just need to store two dates (two points in time) and subtract endTime - StartTime as follow:

import UIKit

class ViewController: UIViewController {

    var startTime: TimeInterval = 0
    var endTime: TimeInterval = 0

    override func viewDidLoad() {
        super.viewDidLoad()
        startTime = Date().timeIntervalSinceReferenceDate
    }

    @IBAction func stopTimeAction(_ sender: Any) {
        endTime = Date().timeIntervalSinceReferenceDate
        print((endTime-startTime).time)
    }

}

---

extension TimeInterval {
    var time: String { .init(format: "%d:%02d:%02d.%03d", Int(self/3600),
                        Int((self/60).truncatingRemainder(dividingBy: 60)),
                        Int(truncatingRemainder(dividingBy: 60)),
                        Int((self*1000).truncatingRemainder(dividingBy: 1000))) }
}