Update
With Swift 5.7, everything below becomes obsolete. Swift 5.7 introduces the concept of a Clock which has a function designed to do exactly what is required here.
There are two concrete examples of a Clock provided: ContinuousClock and SuspendingClock. The former keeps ticking when the system is suspending and the latter does not.
The following is an example of what to do in Swift 5.7
func doSomething()
{
for i in 0 ..< 1000000
{
if (i % 10000 == 0)
{
print(i)
}
}
}
let clock = ContinuousClock()
let result = clock.measure(doSomething)
print(result) // On my laptop, prints "0.552065882 seconds"
It also allows you to measure closures directly, of course
let clock = ContinuousClock()
let result = clock.measure {
for i in 0 ..< 1000000
{
if (i % 10000 == 0)
{
print(i)
}
}
}
print(result) // "0.534663798 seconds"
Pre Swift 5.7
Here's a Swift function I wrote to measure Project Euler problems in Swift
As of Swift 3, there is now a version of Grand Central Dispatch that is "swiftified". So the correct answer is probably to use the DispatchTime API.
My function would look something like:
// Swift 3
func evaluateProblem(problemNumber: Int, problemBlock: () -> Int) -> Answer
{
print("Evaluating problem \(problemNumber)")
let start = DispatchTime.now() // <<<<<<<<<< Start time
let myGuess = problemBlock()
let end = DispatchTime.now() // <<<<<<<<<< end time
let theAnswer = self.checkAnswer(answerNum: "\(problemNumber)", guess: myGuess)
let nanoTime = end.uptimeNanoseconds - start.uptimeNanoseconds // <<<<< Difference in nano seconds (UInt64)
let timeInterval = Double(nanoTime) / 1_000_000_000 // Technically could overflow for long running tests
print("Time to evaluate problem \(problemNumber): \(timeInterval) seconds")
return theAnswer
}
Old answer
For Swift 1 and 2, my function uses NSDate:
// Swift 1
func evaluateProblem(problemNumber: Int, problemBlock: () -> Int) -> Answer
{
println("Evaluating problem \(problemNumber)")
let start = NSDate() // <<<<<<<<<< Start time
let myGuess = problemBlock()
let end = NSDate() // <<<<<<<<<< end time
let theAnswer = self.checkAnswer(answerNum: "\(problemNumber)", guess: myGuess)
let timeInterval: Double = end.timeIntervalSinceDate(start) // <<<<< Difference in seconds (double)
println("Time to evaluate problem \(problemNumber): \(timeInterval) seconds")
return theAnswer
}
Note that using NSdate for timing functions is discouraged: "The system time may decrease due to synchronization with external time references or due to an explicit user change of the clock.".
sqrt(number)instead ofnumber, and you can save a little more time – but there are much more ideas optimising seeking primes. – CavorelievoNSDateobjects and you can measure the difference between them. – Cavorelievo