The challenge I had was trying to break down date info for an app that was going to keep track of the current week as well as the current day. For that, I really needed to figure out how to break out these parts into something I could use.
After a little looking online, I found some hints and I put together the below in a swift playground. It is not comprehensive but should get you started.
import Cocoa import Foundation //Get the date let date = NSDate() // Define the parts you want let flags: NSCalendarUnit = NSCalendarUnit.CalendarUnitDay | NSCalendarUnit.CalendarUnitMonth | NSCalendarUnit.CalendarUnitYear | NSCalendarUnit.CalendarUnitWeekOfYear | NSCalendarUnit.CalendarUnitWeekdayOrdinal | NSCalendarUnit.CalendarUnitWeekday // Setup the calculator class let cal = NSCalendar.currentCalendar() // combine the parts desired with the current date into the components variable. let components = cal.components(flags, fromDate: date) //The Parts println(components.year) println(components.month) println(components.day) println(components.weekOfYear) println(components.weekdayOrdinal) println(components.weekday) //Gets day of the year let day = cal.ordinalityOfUnit(.CalendarUnitDay, inUnit: .CalendarUnitYear, forDate: date)