Get the Week Number in iOS SDK

Question

I want to get the Week number of the year from the date.I tried the code as follow but gives me a wrong week number.

My code for week number:

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"YYYY-MM-dd"];
    NSDate *date = [dateFormatter dateFromString:@"2012-09-15"];


    NSCalendar *calendar = [NSCalendar currentCalendar];

    NSLog(@"week: %i", [[calendar components: NSWeekOfYearCalendarUnit fromDate:date] weekOfYear]); //Display 38 instead of 37
}

Note: If i try with with [NSDate date] display the correct.

Help me to solve this.. Thank you,

see my answer http://stackoverflow.com/questions/17403761/get-the-day-from-the-date-in-ios-sdk/17403855#17403855 — SAMIR RATHOD, Jul 11 '13 at 07:47
There are different definitions for the week number of a date. I think that's the most likely cause of your problem. See http://en.wikipedia.org/wiki/Calendar_week#Week_numbering for details. — Treb, Jul 11 '13 at 07:47
@SAMIRRATHOD,Thanks for reply... it just shows about the week day not for the week number . — user2526811, Jul 11 '13 at 07:49

Misha Vyrko · Accepted Answer · 2020-07-27T19:37:10.913

ObjectiveC:

 NSCalendar *calendar = [NSCalendar currentCalendar];
 NSDateComponents *dateComponent = [calendar components:(NSWeekOfYearCalendarUnit | NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit) fromDate:[NSDate date]];
 NSLog(@"%@",dateComponent);

Update

 NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *dateComponent = [calendar components:(NSCalendarUnitWeekOfYear | NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear) fromDate:date];
    NSLog(@"%@",dateComponent);

Swift:

let calendar = NSCalendar.currentCalendar()
let dateComponent = calendar.components([.WeekOfYear, .Day, .Month, .Year], fromDate: NSDate(timeIntervalSinceNow: 0))
print("weekOfYear \(dateComponent.weekOfYear)")

Swift 3 - Swift 5:

let component = Calendar.current.component(.weekOfYear, from: Date())
print("Week of Year \(component)")

Thanks for reply.. But when i try to give the date from String as seen above, it returns the wrong week number. — user2526811, Jul 11 '13 at 07:51

AlexVogel · Answer 2 · 2013-07-11T08:35:54.237

11

[NSCalendar currentCalendar] gives you a Gregorian Calendar as default. You can use

NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSISO8601Calendar];

to get an ISO 08601 conform calendar, which has week number 37 for your date.

edited Jul 11 '13 at 08:35

answered Jul 11 '13 at 07:58

AlexVogel

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sorry but for the `2012-09-25`, it returns _38 instead of 39_. **What's going wrong now?** – user2526811 Jul 11 '13 at 09:05
try to set the first week day of the calendar to the correct value (I don't know which ..) with - (void)setFirstWeekday:(NSUInteger)weekday – AlexVogel Jul 11 '13 at 09:25

score 0 · Answer 3 · answered Dec 02 '16 at 10:02

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Swift 3: You need know last Date of selected month. Than check number of week for this week, and this will be your number of weeks in month

return Calendar.current.component(.weekOfMonth, from: lastDate ?? Date())

answered Dec 02 '16 at 10:02

Konstantin Kryzhanovsky

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score 0 · Answer 4 · answered Nov 16 '17 at 12:09

Updated code in ObjectiveC used Xcode version - 9.1 - :

    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *dateComponent = [calendar components:(NSCalendarUnitWeekOfYear | NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear) fromDate:[NSDate date]];
    NSLog(@"%ld",(long)[dateComponent weekOfYear]);

Get the Week Number in iOS SDK

4 Answers4

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