Calculating actual day's midnight date

Question

Possible Duplicate:
Getting date from [NSDate date] off by a few hours

I want to calculate the actual day's midnight time using the actual day's date here is the code:

NSDateFormatter *formatter = [[NSDateFormatter alloc]init];
    [formatter setDateFormat:@"dd/MM/yyyy"];
 NSDate *today = [NSDate date];
    NSString *todayStr = [NSString stringWithFormat:@"%@ 12:59 PM",[formatter stringFromDate:today]];
NSLog(@"%@",todayStr);
[formatter setDateFormat:@"dd/MM/yyyy hh:mm a"];
NSDate *midNight = [formatter dateFromString:todayStr];
NSLog(@"%@",midNight);

But the log I get is :

23/01/2013 12:59 PM
2013-01-23 10:59:00 +0000

Why does midNight isn't the actual midnight and why does it have a different format from formatter?

score 1 · Answer 1 · answered Jan 23 '13 at 17:17

1

The midnight you calculated with date formatter takes the localization into account.

So, you are living in a UTC+2 timezone.

You can add a 'Z' for UTC.

See more at http://www.w3.org/TR/NOTE-datetime

answered Jan 23 '13 at 17:17

ZhangChn

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I don't get where to add the 'Z' – user32984902578 Jan 23 '13 at 17:30
1994-11-05T13:15:30Z is UTC time, while 1994-11-05T13:15:30 is local time. – ZhangChn Jan 23 '13 at 17:35
So how should I modify my code? – user32984902578 Jan 23 '13 at 17:50
I don't see what else you want or anything wrong. – ZhangChn Jan 23 '13 at 18:29

Bart Whiteley · Answer 2 · 2013-01-23T19:04:53.447

0

This calculates midnight for your local timezone.

NSDate *d = [NSDate date];
NSCalendar *cal = [NSCalendar currentCalendar];
NSDateComponents *comps = [cal components:NSEraCalendarUnit|NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit fromDate:d];
d = [cal dateFromComponents:comps];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"dd/MM/yyyy hh:mm a"];
NSString *dateStr = [formatter stringFromDate:d];
NSLog(@"%@", dateStr);

prints 23/01/2013 12:00 AM

edited Jan 23 '13 at 19:04

answered Jan 23 '13 at 18:30

Bart Whiteley

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You might want to add NSEraCalendarUnit just for completeness. – Fabian Kreiser Jan 23 '13 at 18:32
I'm getting `2013-01-22 22:00:00 +0000` as date for `d`... – user32984902578 Jan 23 '13 at 18:38
Good point Fabian. I updated the code. – Bart Whiteley Jan 23 '13 at 18:44
moray95: When you log the NSDate, it prints in UTC time. Use NSDateFormatter to print it for your local timezone. – Bart Whiteley Jan 23 '13 at 18:52
moray95: You're already doing it in the initial question. I expanded the code also. – Bart Whiteley Jan 23 '13 at 19:05

Calculating actual day's midnight date

2 Answers2