NSDateFormatter in 12-hour mode

Question

I have the following code.

NSDateFormatter *df = ...;
[df setTimeZone:[NSTimeZone defaultTimeZone]];
[df setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss.SSSZZZ"];
NSDate * date = [df dateFromString:date_string]; //here is the problem

In 24-hour mode everything is ok. When 12-hour mode is set on device, stringFromDate returns null. Format of date_string is the same all the time, date format too. Why does it happen?

can u display the date_string value! – Dinesh Jun 16 '12 at 09:33 — Dinesh, Jun 16 '12 at 09:33
2012-06-16T10:00:47.436+0000 for instance – Sergey Jun 16 '12 at 10:02 — Sergey, Jun 16 '12 at 10:02
See [this post](http://stackoverflow.com/q/6613110/581994). – Hot Licks Jun 16 '12 at 13:01 — Hot Licks, Jun 16 '12 at 13:01

score 55 · Answer 1 · answered Jun 16 '12 at 09:34

55

In your NSDateFormatter "yyyy-MM-dd'T'HH:mm:ss.SSSZZZ" HH stands for 24 hour and hh stands for 12 hour

answered Jun 16 '12 at 09:34

Omar Abdelhafith

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I want to ignore 12-hour system settings and don't know how – Sergey Jun 16 '12 at 10:12
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@Sergey then use **hh** instead of **HH** – Omar Abdelhafith Jun 16 '12 at 10:13
join this chat room http://chat.stackoverflow.com/rooms/info/12634/chat-nsdateformatter?tab=general – Omar Abdelhafith Jun 16 '12 at 10:24
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This is not true. If user has 24 hour turned off and uses HH, it will still be 12 hour format. – Zeezer May 26 '16 at 15:23
And if you like to add AM / PM, add letter "a" at the end of your format string like this: "hh:mm a" – Luiz Dias Sep 15 '20 at 18:21

aleroot · Accepted Answer · 2012-06-16T12:24:26.990

37

Try to set the locale in this way :

NSLocale *twelveHourLocale = [[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"];
df.locale = twelveHourLocale;

To force instead to 24 hour, you can use :

NSLocale *twentyFour = [[NSLocale alloc] initWithLocaleIdentifier:@"en_GB"];

edited Jun 16 '12 at 12:24

answered Jun 16 '12 at 09:35

aleroot

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I would like to force dateformatter to ignore 12-hour mode and use 24-hour all the time. What loc identifier should I use? – Sergey Jun 16 '12 at 10:09
en_GB --> NSLocale* formatterLocale = [[[NSLocale alloc] initWithLocaleIdentifier:@"en_GB"] autorelease]; – aleroot Jun 16 '12 at 12:23
Brilliant! Works like a charm. – Fogmeister Oct 03 '13 at 08:37
Do not recommend. "hh" means 12 hour, and "HH" means 24 hour – DawnSong Jun 27 '19 at 17:30

score 6 · Answer 3 · answered Jan 11 '13 at 10:31

12-hour mode to 24 hour mode:

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"hh:mm a"];
NSDate *amPmDate = [formatter dateFromString:amPmHourString];
[formatter setDateFormat:@"HH:mm"];
NSString *24HourString = [formatter stringFromDate:amPmDate]];

For 24-hour mode to 12 hour mode just do the opposite

score 4 · Answer 4 · answered Oct 29 '15 at 14:47

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NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
NSLocale *locale = [[[NSLocale alloc] 
                initWithLocaleIdentifier:@"en_US_POSIX"] autorelease];  
[dateFormat setLocale:locale];

answered Oct 29 '15 at 14:47

Sagar Desai

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NSDateFormatter in 12-hour mode

4 Answers4

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