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Precision Timing in iOS/OSX/Swift
//: Playground - noun: a place where code can play
import UIKit
//Most precise time keeper
// for more information on the benchmarks go to www.kandelvijaya.com
func timeBlockWithMach(_ block: () -> Void) -> TimeInterval {
var info = mach_timebase_info()
guard mach_timebase_info(&info) == KERN_SUCCESS else { return -1 }
let start = mach_absolute_time()
block()
let end = mach_absolute_time()
let elapsed = end - start
let nanos = elapsed * UInt64(info.numer) / UInt64(info.denom)
return TimeInterval(nanos) / TimeInterval(NSEC_PER_SEC)
}
func test() {
let rtDate = timeBlockWithMach{
NSDate().timeIntervalSince1970
}
let rtMedia = timeBlockWithMach {
CACurrentMediaTime()
}
let rtAbsolute = timeBlockWithMach {
CFAbsoluteTimeGetCurrent()
}
var time = timeval()
let rtTimeOfDay = timeBlockWithMach {
gettimeofday(&time, nil)
}
let rtTimeWithMach = timeBlockWithMach {
mach_absolute_time()
}
let rtTimeWithProcessInfo = timeBlockWithMach {
ProcessInfo.processInfo.systemUptime
}
}
test()
// MARK: - Other timing functions
func timeBlockWithDateTime(_ block: () -> Void) -> TimeInterval {
let start = NSDate().timeIntervalSince1970
block()
let end = NSDate().timeIntervalSince1970
return end - start
}
func timeBlockWithCAMediaTiming(_ block: () -> Void) -> TimeInterval {
let start = CACurrentMediaTime()
block()
let end = CACurrentMediaTime()
return end - start
}
func timeBlockWithCFTime(_ block: () -> Void) -> TimeInterval {
let start = CFAbsoluteTimeGetCurrent()
block()
let end = CFAbsoluteTimeGetCurrent()
return end - start
}
func timeBlockWithGetTimeOfDay(_ block: () -> Void) -> TimeInterval {
var start = timeval()
gettimeofday(&start, nil)
block()
var end = timeval()
gettimeofday(&end, nil)
return Double(start.tv_usec - end.tv_usec)
}
Owner

kandelvijaya commented Oct 24, 2016

When benchmarking using the above functions, its always a good idea to run the code/function/block in a loop of several 100 times and average the running time to get a proximate time. Running time of a code is different at different times. However, the ratio of running time for 2 different code is equivalent.

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