Get the first day of week without WeekCalendarUnit

问题

I would like to get the first day of the week depending on a NSDate.

It works fine but I have a warning because WeekCalendarUnit is deprecated.

I made some research and I tried to replace WeekCalendarUnit with :

static var CalendarUnitWeekday: NSCalendarUnit { get }
static var CalendarUnitWeekdayOrdinal: NSCalendarUnit { get }
static var CalendarUnitWeekOfMonth: NSCalendarUnit { get }
static var CalendarUnitWeekOfYear: NSCalendarUnit { get }

But I don't have the same result. Here is my junk of code :

var date = NSDate()
dateFormatter.dateFormat = "dd/YY"
let calendar = NSCalendar.currentCalendar()
let currentDateComponents = calendar.components(.CalendarUnitYear | .WeekCalendarUnit , fromDate: date)
let startOfWeek = calendar.dateFromComponents(currentDateComponents)
var dteString = dateFormatter.stringFromDate(startOfWeek!)
// Output is "17/15"

Any Idea?

回答1:

You can use .CalendarUnitWeekOfYear in combination with .CalendarUnitYearForWeekOfYear, this should give the intended result:

let currentDateComponents = calendar.components(.CalendarUnitYearForWeekOfYear | .CalendarUnitWeekOfYear , fromDate: date)
let startOfWeek = calendar.dateFromComponents(currentDateComponents)

Alternatively, use rangeOfUnit() (which I personally find easier to use):

var startOfWeek : NSDate?
calendar.rangeOfUnit(.CalendarUnitWeekOfYear, startDate: &startOfWeek, interval: nil, forDate: date)

In Swift 2 this has to be changed to

let currentDateComponents = calendar.components([.YearForWeekOfYear, .WeekOfYear ], fromDate: date)
let startOfWeek = calendar.dateFromComponents(currentDateComponents)

and

var startOfWeek : NSDate?
calendar.rangeOfUnit(.WeekOfYear, startDate: &startOfWeek, interval: nil, forDate: date)

来源：https://stackoverflow.com/questions/30330523/get-the-first-day-of-week-without-weekcalendarunit

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swift

nsdate