How to get the number of weeks in a month

Question

Here is the problem, i'm looking for a way to get the number of weeks in a month. I already find a solution that seems to work on ios 5, but it not on io6 (number returned is not the same, one more on ios 6).

- (int)weeksOfMonth:(int)month inYear:(int)year
{
    NSCalendar *cCalendar = [NSCalendar currentCalendar];

    NSDateComponents *components = [[NSDateComponents alloc] init];
    [components setMonth:month];
    [components setYear:year];

    NSRange range = [cCalendar rangeOfUnit:NSDayCalendarUnit
                               inUnit:NSMonthCalendarUnit
                              forDate:[cCalendar dateFromComponents:components]];

    cCalendar = [NSCalendar currentCalendar];
    [cCalendar setMinimumDaysInFirstWeek:4];

    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init];
    [dateFormatter setLocale: [[NSLocale alloc] initWithLocaleIdentifier:@"fr"]];
    [dateFormatter setDateFormat:@"yyyy-MM-dd"];
    NSMutableSet *weeks = [[NSMutableSet alloc] init ];

    for(int i = 0; i < range.length; i++)
    {
        NSString *temp = [NSString stringWithFormat:@"%4d-%2d-   %2d",year,month,range.location+i];
        NSDate *date = [dateFormatter dateFromString:temp ];
        int week = [[cCalendar components: NSWeekOfYearCalendarUnit fromDate:date] weekOfYear];
        [weeks addObject:[NSNumber numberWithInt:week]];
    }

    return [weeks count];
}

The returned value is 6 on io6 and 5 on io5.

Do you have any idea ?

EDIT : Another thing, my device (ios5) is in French and the simulator (ios6) is in English. Maybe it can change something (like the first day of week ?) ?

What is the month and year you're trying that shows the problem? — occulus, Mar 06 '13 at 09:41
Check my updatd code, and i check it in osx and ios6, it works fine. — Anoop Vaidya, Mar 06 '13 at 10:40
This is tested with March 2013, and the result should be 5, except if weeks starts on sunday. Maybe the problem is here. (The simulator (io6) is on english and my device (on ios5) on french). — R.Lambert, Mar 06 '13 at 18:00
possible duplicate of [Number of weeks in month](http://stackoverflow.com/questions/1805687/number-of-weeks-in-month) — Taryn, Mar 08 '13 at 02:05

score 17 · Accepted Answer · edited Feb 17 '18 at 17:57

Try this one :

NSDate *date = [NSDate date];//since you are forming date, put it here
NSCalendar *calender = [NSCalendar currentCalendar];
NSRange weekRange = [calender rangeOfUnit:NSWeekCalendarUnit inUnit:NSMonthCalendarUnit forDate:date];
NSInteger weeksCount=weekRange.length;
NSLog(@"%d",weeksCount);

Swift 4.0:

let date = Date()
let calendar = Calendar.current
let weekRange = calendar.range(of: .weekOfMonth, 
                               in: .month, 
                               for: date)
let weeksCount = weekRange.count ?? 0
print(weeksCount)

Or change your method to :

- (NSInteger)weeksOfMonth:(int)month inYear:(int)year{
    NSString *dateString=[NSString stringWithFormat:@"%4d/%d/1",year,month];

    NSDateFormatter *dfMMddyyyy=[NSDateFormatter new];
    [dfMMddyyyy setDateFormat:@"yyyy/MM/dd"];
    NSDate *date=[dfMMddyyyy dateFromString:dateString];

    NSCalendar *calender = [NSCalendar currentCalendar];
    NSRange weekRange = [calender rangeOfUnit:NSWeekCalendarUnit inUnit:NSMonthCalendarUnit forDate:date];
    NSInteger weeksCount=weekRange.length;

    return weeksCount;
}

EDIT:

use this in above method

 //NSCalendar *calender = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
 [calender setFirstWeekday:2]; //sunday=1, monday=2 etc

Thank you for your code but the result does not change, I still have 5 on my device (ios5) and 6 on simulator (ios6). I forgot one thing, maybe it's a localization problem, maybe in french (like my device is) week starts on monday (what I want) but not in english ? — R.Lambert, Mar 06 '13 at 18:04
There you go, this is the problem, however you got a shorter solution above. — Anoop Vaidya, Mar 06 '13 at 18:06

score 0 · Answer 2 · edited Dec 06 '17 at 05:50

Check this approach.

-(NSArray*)getWeekDaysForDate {


int dayOfWeek = [self weekDay];

NSMutableArray *array = [NSMutableArray array];

NSDate *weekStartDate = [self offsetDay:1-dayOfWeek];

NSCalendar *calendar = [NSCalendar defaultCalendar];
NSInteger monthValue = [self month];
unsigned int weekNum = [[calendar components: NSWeekCalendarUnit
                               fromDate: weekStartDate] week];
NSDate * nextDate = weekStartDate, *curDate;
NSDateComponents *oneDay = [[NSDateComponents alloc] init];
[oneDay setDay:1];
unsigned int newWeekNum;
do {
    curDate = nextDate;
    nextDate = [calendar dateByAddingComponents:oneDay toDate: curDate
                                   options:0];

    newWeekNum = [[calendar components: NSWeekCalendarUnit fromDate:
                   nextDate] week];
    int monthValueForNextDate = [[calendar components: NSMonthCalendarUnit fromDate:
                       nextDate] month];

    if(monthValue == monthValueForNextDate)
        [array addObject:nextDate]];

} while (newWeekNum == weekNum);

[array sortUsingSelector:@selector(compare:)];

return array;
}

-(int)month {
   NSCalendar *gregorian = [NSCalendar defaultCalendar];
   NSDateComponents *components = [gregorian components:NSMonthCalendarUnit fromDate:self];
   return [components month];
}

-(int)weekDay {
   NSCalendar *gregorian = [NSCalendar defaultCalendar];
   NSDateComponents *components = [gregorian components:NSWeekdayCalendarUnit fromDate:self];
   return [components weekday];
}

-(NSDate *)offsetDay:(int)numDays {
   NSCalendar *gregorian = [NSCalendar defaultCalendar];
   NSDateComponents *offsetComponents = [[NSDateComponents alloc] init];
   [offsetComponents setDay:numDays];
   return [gregorian dateByAddingComponents:offsetComponents
                                  toDate:self options:0];
}

PS: NSCalendar defaultCalendar = [[NSCalendar alloc]initWithCalendarIdentifier:NSGregorianCalendar];

Adding this method then the category of NSDate will return the weekdays of any date that lies in the same week.

Best Regards.

How to get the number of weeks in a month

2 Answers2