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

NSDate is tied to the realtime clock on iOS and Mac devices, and has sub-millisecond accuracy.

Use NSDate's timeIntervalSinceReferenceDate method to convert an NSDate (or the current time) to a double that is the number of seconds since January 1, 2001, including fractional seconds. Once you do that you're free to do math on the doubles that you get back.