On Apr 27, 2010, at 10:45 PM, Scott Ribe wrote: > I have an int representing the number of days since 1/1/2001, and wish to get > an NSDate representing that date in the system's local time zone: > > NSDateComponents *dc = [[[NSDateComponents alloc] init] autorelease]; > [dc setDay: numdays]; > NSDate * cd = [[NSCalendar currentCalendar] dateByAddingComponents: dc > toDate: [NSDate dateWithString: @"2001-01-01"] options: 0]; > NSLog( @"date 1: %@", [cd description] ); > [dc setDay: 0]; > [dc setSecond: -[[NSTimeZone systemTimeZone] secondsFromGMTForDate: cd]]; > cd = [[NSCalendar currentCalendar] dateByAddingComponents: dc toDate: cd > options: 0]; > NSLog( @"date 2: %@", [cd description] ); > > If for example numdays is the number of days from 1/1/2001 to 5/4/2010, then > the output is this: > > 2010-04-27 21:33:55.803 PedCard[95387:a0f] date 1: 2010-05-03 17:00:00 -0600 > 2010-04-27 21:33:55.804 PedCard[95387:a0f] date 2: 2010-05-03 23:00:00 -0600 > > And, BTW, my current time zone is MDT, so -0600 is not correct, it should be > -0700. So what's going on? I would expect those dates to be: > > 2010-05-03 17:00:00 -0700 > 2010-05-04 00:00:00 -0700 >
MDT is -0600 so this is correct - MST is -0700. (stupid "spring forward, fall back" clock resetting...) I find that dealing with dates and time zones it's best to consider NSDate to be just a scalar value, with a separate time zone (and optional calendar) being the "unit". It's up to the formatter used to display that (scalar) date in the desired unit. Glenn Andreas gandr...@gandreas.com The most merciful thing in the world ... is the inability of the human mind to correlate all its contents - HPL _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
