CODEWITHSUNDEEP
cocoa-touchiphone-sdk-3.0ios4nsdatensdateformatter
Raj Pawan Gumdal
Raj Pawan Gumdal

Reputation: 7438

NSDateFormatter returns nil for @"dd-MM-yy" in iOS 3.0

I have this part of code:

NSDate *date =nil;
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateStyle:NSDateFormatterMediumStyle];
[dateFormatter setDateFormat:@"dd-MM-yy"];
date = [dateFormatter dateFromString:inString];
[dateFormatter release];

It works perfectly fine, as expected in iOS 4.0. But the same code doesnt in 3.0.

The string which I am getting, is like "12-Nov-10" and this is contained in inString pointer.

The date formatter returns nil if the native OS is 3.0 or 3.1. For some reasons I need to stick to the same date format. Has anyone else faced this problem? Any suggestions to resolve this issue?

Thanks,

Raj

Edit: The proper code, after following suggestions pointed out by Harkonian and the Q&A discussions:

NSDate *date =nil;
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateStyle:NSDateFormatterMediumStyle];
[dateFormatter setDateFormat:@"dd-MMM-yy"];

NSLocale *enUSPOSIXLocale = [[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"];
[dateFormatter setLocale:enUSPOSIXLocale];
[enUSPOSIXLocale release];

date = [dateFormatter dateFromString:inString];
[dateFormatter release];

Upvotes: 2

Views: 6203

Answers (2)

Raj Pawan Gumdal
Raj Pawan Gumdal

Reputation: 7438

An extremely useful page does not exist anymore, so just putting its content here for archival purpose:

a:  AM/PM
A:  0~86399999 (Millisecond of Day)

c/cc:   1~7 (Day of Week)
ccc:    Sun/Mon/Tue/Wed/Thu/Fri/Sat
cccc:   Sunday/Monday/Tuesday/Wednesday/Thursday/Friday/Saturday

d:  1~31 (0 padded Day of Month)
D:  1~366 (0 padded Day of Year)

e:  1~7 (0 padded Day of Week)
E~EEE:  Sun/Mon/Tue/Wed/Thu/Fri/Sat
EEEE:   Sunday/Monday/Tuesday/Wednesday/Thursday/Friday/Saturday

F:  1~5 (0 padded Week of Month, first day of week = Monday)

g:  Julian Day Number (number of days since 4713 BC January 1)
G~GGG:  BC/AD (Era Designator Abbreviated)
GGGG:   Before Christ/Anno Domini

h:  1~12 (0 padded Hour (12hr))
H:  0~23 (0 padded Hour (24hr))

k:  1~24 (0 padded Hour (24hr)
K:  0~11 (0 padded Hour (12hr))

L/LL:   1~12 (0 padded Month)
LLL:    Jan/Feb/Mar/Apr/May/Jun/Jul/Aug/Sep/Oct/Nov/Dec
LLLL:   January/February/March/April/May/June/July/August/September/October/November/December

m:  0~59 (0 padded Minute)
M/MM:   1~12 (0 padded Month)
MMM:    Jan/Feb/Mar/Apr/May/Jun/Jul/Aug/Sep/Oct/Nov/Dec
MMMM:   January/February/March/April/May/June/July/August/September/October/November/December

q/qq:   1~4 (0 padded Quarter)
qqq:    Q1/Q2/Q3/Q4
qqqq:   1st quarter/2nd quarter/3rd quarter/4th quarter
Q/QQ:   1~4 (0 padded Quarter)
QQQ:    Q1/Q2/Q3/Q4
QQQQ:   1st quarter/2nd quarter/3rd quarter/4th quarter

s:  0~59 (0 padded Second)
S:  (rounded Sub-Second)

u:  (0 padded Year)

v~vvv:  (General GMT Timezone Abbreviation)
vvvv:   (General GMT Timezone Name)

w:  1~53 (0 padded Week of Year, 1st day of week = Sunday, NB: 1st week of year starts from the last Sunday of last year)
W:  1~5 (0 padded Week of Month, 1st day of week = Sunday)

y/yyyy: (Full Year)
yy/yyy: (2 Digits Year)
Y/YYYY: (Full Year, starting from the Sunday of the 1st week of year)
YY/YYY: (2 Digits Year, starting from the Sunday of the 1st week of year)

z~zzz:  (Specific GMT Timezone Abbreviation)
zzzz:   (Specific GMT Timezone Name)
Z:  +0000 (RFC 822 Timezone)

Upvotes: 10

memmons
memmons

Reputation: 40502

If you're working with user-visible dates, you should avoid setting a date format string because it's very hard to predict how your format string will be expressed in all possible user configurations. Rather, you should try and limit yourself to setting date and time styles (via -[NSDateFormatter setDateStyle:] and -[NSDateFormatter setTimeStyle:]).

On the other hand, if you're working with fixed-format dates, you should first set the locale of the date formatter to something appropriate for your fixed format. In most cases the best locale to choose is "en_US_POSIX", a locale that's specifically designed to yield US English results regardless of both user and system preferences. "en_US_POSIX" is also invariant in time (if the US, at some point in the future, changes the way it formats dates, "en_US" will change to reflect the new behaviour, but "en_US_POSIX" will not), and between machines ("en_US_POSIX" works the same on iPhone OS as it does on Mac OS X, and as it it does on other platforms).

Once you've set "en_US_POSIX" as the locale of the date formatter, you can then set the date format string and the date formatter will behave consistently for all users.

The above info and more can be found in Apple's Technical Q&A QA1480

Here's a snippet of code from my app which implements the above recommendation :

static NSDateFormatter* dateFormatter = nil;
if (!dateFormatter) {
   dateFormatter = [[NSDateFormatter alloc] init];

   NSLocale *enUSPOSIXLocale = [[[NSLocale alloc] 
      initWithLocaleIdentifier:@"en_US_POSIX"] autorelease];
   assert(enUSPOSIXLocale != nil);
   [dateFormatter setLocale:enUSPOSIXLocale];
   [dateFormatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
   dateFormatter.dateFormat = @"EEE, dd MMM yyyy HH:mm:ss +0000";
}

Upvotes: 7

Related Questions