calculate week numbers given month

Question

I want to calculate the week numbers in a given month. example the month july 2012 should have week number 26, 27, 28, 29, 30 and 31. I cooked up this snippet, but I looking for a workable way to get the preceding and succeeding week numbers. Any idea's.

Thanks, Darrell.

//Get current week number
NSCalendar *cal = [NSCalendar currentCalendar];
NSDateComponents *components = [cal components:NSWeekCalendarUnit fromDate:[NSDate date]];
NSInteger week = [components week];
NSLog(@"Week nummer: %d", (int)week);

//Get week numbers in month
[components weekOfYear];
NSRange weeksInMonth = [cal rangeOfUnit:NSWeekCalendarUnit
                          inUnit:NSMonthCalendarUnit
                         forDate:[cal dateFromComponents:components]];
NSLog(@"Weken in maand: %lu", weeksInMonth.length);

Answer 1

Function:

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

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

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

    calendar = [NSCalendar currentCalendar];
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init];
    [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 = [[calendar components: NSWeekOfYearCalendarUnit fromDate:date] weekOfYear];
        [weeks addObject:[NSNumber numberWithInt:week]];
    }

    NSSortDescriptor *descriptor = [[NSSortDescriptor alloc] initWithKey:@"" ascending:YES];
    NSArray *descriptors = [[NSArray alloc] initWithObjects:descriptor, nil];
    return [weeks sortedArrayUsingDescriptors:descriptors];
}

Usage:

NSArray *weeks = [self weeksOfMonth:7 inYear:2012];
NSLog(@"%@",weeks);

Output:

{(
    27,
    28,
    29,
    30,
    31
)}