EasterDate

Introduction

This module adds Easter date calculation class methods to NSDate. It's written in Swift and runs on various platforms:

Swift 2.2 on iOS, tvOS, Mac OS X, Linux
Swift 3.0 on iOS, tvOS, Mac OS X, Linux

It can be installed with CocoaPods or Swift Package Manager.

Usage

Western Easter

To calculate the date of Western Easter for a given year:

import EasterDate

let easter = NSDate.westernEasterDate(2016)
// easter is an NSDate

To calculate Western Easter Sunday for this year:

// Get current year (Swift 2.2)
let year = NSCalendar.currentCalendar().components([.Year], fromDate: NSDate()).year

// Get current year (Swift 3.0)
let year = NSCalendar.current().components([.year], from: NSDate()).year

// Get current year (Swift 3.0, Linux)
let year = NSCalendar.current().components([.year], from: NSDate())!.year

// Get Easter for year
let easter = NSDate.westernEasterDate(year: year)

Eastern Orthodox Easter

To calculate the date of Eastern Orthodox Easter for a given year:

import EasterDate

let easter = NSDate.easternOrthodoxEasterDate(2016)
// easter is an NSDate

Note that while the calculation for Eastern Orthodox Easter is based on the Julian calendar, the date returned is in the Gregorian calendar.

To calculate Eastern Orthodox Easter Sunday for this year:

// Get current year (Swift 2.2)
let year = NSCalendar.currentCalendar().components([.Year], fromDate: NSDate()).year

// Get current year (Swift 3.0)
let year = NSCalendar.current().components([.year], from: NSDate()).year

// Get current year (Swift 3.0, Linux)
let year = NSCalendar.current().components([.year], from: NSDate())!.year

// Get Easter for year
let easter = NSDate.easternOrthodoxEasterDate(year: year)

Examples

The included example project provides build targets for three platforms: iOS, tvOS and Mac OS X. Each provides a very simple interface to view the Western and Eastern Orthodox dates for Easter Sunday for a selected year, along with a method of selecting years. There's nothing complex or exciting in these examples - they're more to demonstrate that the build environment works properly!

To run them, you'll need to clone the Git repository and refresh the CocoaPods:

# Clone the repository
git clone https://github.com/threebytesfull/EasterDate.git

# cd into the Example directory
cd EasterDate/Example

# Refresh the CocoaPods
pod install

Open the .xcworkspace file in the Example directory and you can build any of the supplied example targets.

Linux

The project includes a shell script, test-linux.bash which uses Docker to start up a Linux environment with a development snapshot of Swift 3.0 and run the EasterDate unit tests.

Requirements

This module supports Swift 2.2 and Swift 3.0 (tested so far with the 2016-05-31-a development snapshot) on OS X, iOS, tvOS and Linux.

Installation

EasterDate is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod "EasterDate"

Author

Rufus Cable, rufus@threebytesfull.com

Credits

The date calculation algorithms are not mine. Both come from Wikipedia:

License

EasterDate is available under the MIT license. See the LICENSE file for more info.