Question

I execute following snippet of code:

NSCalendar *gregorian = [[NSCalendar alloc]initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *comp = [gregorian components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit) fromDate:[NSDate date]]; 
[comp setDay:1]; 

NSDate *firstDayOfMonthDate = [gregorian dateFromComponents:comp];

The Value of firstDayOfMonthDate is = 30-4-2011 but excpeted is 1-5-2011 i.e I want first date of month of any specified date.
But it gives me the last date of the previous month.

thanks in advance.

Answer 1

Add

[gregorian setTimeZone:[NSTimeZone timeZoneWithAbbreviation:@"UTC"]];

after initializing your NSCalendar.

[NSDate date] will return a date in the UTC timezone, well an absolute interval since January 1, 2001 00:00 GMT, but the NSCalendar has its timeZone set to the default timezone which may not be UTC.

UTC is the “same” as UTC, a quote from wikipedia:

In casual use, when fractions of a
second are not important, Greenwich
Mean Time (GMT) can be considered
equivalent to UTC or UT1. Saying “GMT”
often implies either UTC or UT1 when
used within informal or casual
contexts. In technical contexts, usage
of “GMT” is avoided; the unambiguous
terminology “UTC” or “UT1” is
preferred.[3]