Latest 4.0.0
License Apache License, Version 2.0
Platforms ios 8.0, osx 10.9, tvos 9.0

Kronos is an NTP client library written in Swift. It supports
sub-seconds precision and provides an stable monotonic clock that won’t
be affected by clock changes.

Example app

This is an
example app that displays the monotonic on the left and the
system clock (initially out of date) on the right.



Sync clock using a pool of NTP servers

Calling Clock.sync will fire a bunch of NTP requests to up to 5 of the
servers on the given NTP pool (default is As soon as
we get the first response, the given closure is called but the Clock
will keep trying to get a more accurate response.

Clock.sync { date, offset in
    // This is the first sync (note that this is the fastest but not the
    // most accurate run

Get an NTP sync’ed date is a monotonic NSDate that won’t be affected by clock

NSTimer.scheduledTimerWithTimeInterval(1.0, target: self,
                                       selector: #selector(Example.tick),
                                       userInfo: nil, repeats: true)

@objc func tick() {
    print( // Note that this clock will get more accurate as
                     // more NTP servers respond.


Embedded frameworks require a minimum deployment target of iOS 8 or OS
X Mavericks (10.9).


CocoaPods is a dependency manager for Cocoa projects.
You can install it with the following command:

$ gem install cocoapods

CocoaPods 0.39.0+ is required to build Kronos.

To integrate Kronos into your Xcode project using CocoaPods, specify it in
your Podfile:

platform :ios, '8.0'

pod 'Kronos'

Then, run the following command:

$ pod install

Swift package manager (experimental)

Swift PM is a tool for
managing distribution of source code.

To integrate Kronos into your project using Swift PM use:

$ export SWIFT_EXEC=/Applications/
$ swift build


Carthage is a decentralized dependency manager for Cocoa. You can install it by following the instructions here.

To integrate Kronos into your project using Carthage, specify it in your Cartfile:

github "lyft/Kronos"

Then, run the following command:

$ carthage update

Looking for Kronos for your Android application? Check out Kronos for Android


Kronos is maintained by Lyft and released under
the Apache 2.0 license. See LICENSE for details.

Latest podspec

    "name": "Kronos",
    "version": "4.0.0",
    "license": {
        "type": "Apache License, Version 2.0",
        "file": "LICENSE"
    "summary": "Elegant NTP client in Swift",
    "homepage": "",
    "authors": {
        "Martin Conte Mac Donell": "[email protected]"
    "source": {
        "git": "",
        "tag": "4.0.0"
    "platforms": {
        "ios": "8.0",
        "osx": "10.9",
        "tvos": "9.0"
    "source_files": "Sources/*.swift"

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