Question

So I implemented a UIDatepicker in one of my applications for scheduling and autodialing teleconferences... everything is pretty much ready to go except, while testing I noticed that when the date rolls over from December 26th to December 27th, the year changes to 2010.

I even rolled it forward to 2011... and it changes when December 25th changes to the 26th.... but wait... in 2012, it correctly rolls over on December 31 - January 1... and then its back to 29th-30th in 2013. Is there some kind of astronomical phenomenon I am not aware of going on or does Apple run on some crazy Heechee calendar I don t know of? The calendar app works correctly...

The most likely explanation is I am missing something so obvious that I will slap myself when I realize it. But hey, I haven t slept in... wow I don t remember if its been two days or three. Take pity and help me out here.

UPDATE: So maybe it wasn t something simple. Still looking for an answer here! Am I really the only person who has experienced this?? I ll bet when the end of December rolls around, more people will hit the same roadblock.

UPDATE2: Anyone? Still looking, still not finding...

UPDATE3: Still haven t found a solution. Come on! This is an interesting puzzle!

UPDATE4: Still no answer found. I have submitted the app and it is now in the appstore. Would still like to see this problem solved so I can update the app.

Answer 1

There may be this problem, that when you are on the last week of the month and the week has fewer than 7 days left in current month, then perhaps the API treated the week as the first week of the next month. Since december of 2012 has already 7 days in its last week there is no problem in that month.

I was getting the same problem here, and I solved it.

- (int) currentWeekOfMonth
{
    return CFCalendarGetOrdinalityOfUnit (
           CFCalendarCopyCurrent(),
           kCFCalendarUnitWeek,
           kCFCalendarUnitMonth,
           [self absoluteTime]);
}

my requirement is to show week number and for this i calculate the week number of first week of month and the add this to the total number of week in month.

int currentWeekNumberInYear =   [_calendarInfo currentWeekOfYear];
int currentWeekNumberInMonth = [_calendarInfo currentWeekOfMonth];
currentWeekNumberInYear = currentWeekNumberInYear-currentWeekNumberInMonth +1;
currentWeekNumberInYear = currentWeekNumberInYear<0 ? (NSInteger)[_calendarInfo weeksInMonth] ==5 ?49:48   : currentWeekNumberInYear;

I hope it will be useful to you.

Answer 2

Turns out its the Date format string used to set up the NSDateFormatter that was causing this for me.

"yyyy" corresponds to the 4-digit year, while YYYY corresponds to the year starting from the Sunday of the 1st week of year. Why anyone would want this is anyone s guess, and it would really help if Apple provided a link to their list of format specifiers, but there you go.

Just make sure your format string has the year component in lowercase and it should be sorted.

Answer 3

This post on TUAW describes a similar problem in PhotoBooth on Mac OS X:

http://www.tuaw.com/2009/12/29/beware-photo-booth-time-stamps-its-a-bug-not-a-feature/

One commenter agrees with vikas that it s an end-of-week issue.

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