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SunKit – Swift library about the Sun

SunKit is a Swift package which uses math and trigonometry to compute several information about the Sun. This package has been developed by a team of learners relatively new to the Swift programming language, which means that there could be a lot of space for improvements. Every contribution is welcome.

SunKit was first developed as part of a bigger project: Sunlitt. Even though Sunlitt is not meant to be released as Open Source we decided to wrap the fundamental logic of the app and make an open source library out of it.

To compute Sunrise, Sunset, Golden Hour and so on we only need a CLLocation and the time zone of that location. CoreLocation framework is required for SunKit to work.


SunKit only needs a location and the relative time zone to compute every information you need about the Sun.
Everything is computed locally, no internet connection is needed.

Creating a Sun

// Creating a CLLocation object with the coordinates you are interested in
let naplesLocation: CLLocation = .init(latitude: 40.84014, longitude: 14.25226)

// Timezone for the location of interest. It's highly recommended to initialize it via identifier
let timeZoneNaples: Timezone = .init(identifier: "Europe/Rome") ?? .current

// Creating the Sun instance which will store all the information you need about sun events and his position
var mySun: Sun = .init(location: naplesLocation, timeZone: timeZoneNaples)

Retrieve information

// Creating a Date instance
let myDate: Date = Date() // Your current date

// Setting inside mySun object the date of interest

      // All the following informations are related to the given location for the date that has just been set

// Azimuth of the Sun 

// Altitude of the Sun

// Sunrise Date

// Sunset Date

// Afternoon Golden Hour Start Date

// Afternoon Golden Hour End Date

// To know all the information you can retrieve go to the **Features** section.

Working with Timezones and Dates

To properly show the Sun Date Events use the following DateFormatter.

 //Creting a DateFormatter
 let dateFormatter =  DateFormatter()
 //Properly setting his attributes
 dateFormatter.locale    =  .current
 dateFormatter.timeZone  =  timeZoneNaples  // It shall be the same as the one used to initilize mySun
 dateFormatter.timeStyle = .full
 dateFormatter.dateStyle = .full
 //Printing Sun Date Events with the correct Timezone
 print("Sunrise: \(dateFormatter.string(from: mySun.sunrise))")


  • Sun Azimuth
  • Sun Altitude
  • First Light Time
  • Last Light Time
  • Sunrise Time
  • Solar Noon Time
  • Golden Hour Time
  • Sunset Time
  • Astronomical Sunrise
  • Astronomical Sunset
  • Nautical Sunrise
  • Nautical Sunset
  • Sun Azimuth at Sunrise
  • Sun Azimuth at Sunset
  • Sun Azimuth at Solar Noon
  • Total Daylight Duration
  • Total Night Duration
  • March Equinox
  • June Solstice
  • September Equinox
  • December Solstice


  • NOAA Global Monitoring Division. General Solar Position Calculations: Link.
  • PV Education: Link.
  • Celestial Calculations: A Gentle Introduction to Computational Astronomy: Link.

MoonKit 🌙

Take a look to the other Package, this time about the Moon.

SunKit on GitHub:
Platform: iOS
⭐️: 51