What is the best way to deal with the NSDateFormatter locale "feechur"?
Duh!!
Sometimes you have an "Aha!!" moment, sometimes it's more of a "Duh!!" This is the latter. In the category for initWithSafeLocale
the "super" init
was coded as self = [super init];
. This inits the SUPERCLASS of NSDateFormatter
but does not init
the NSDateFormatter
object itself.
Apparently when this initialization is skipped, setLocale
"bounces off", presumably because of some missing data structure in the object. Changing the init
to self = [self init];
causes the NSDateFormatter
initialization to occur, and setLocale
is happy again.
Here is the "final" source for the category's .m:
#import "NSDateFormatter+Locale.h"@implementation NSDateFormatter (Locale)- (id)initWithSafeLocale { static NSLocale* en_US_POSIX = nil; self = [self init]; if (en_US_POSIX == nil) { en_US_POSIX = [[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"]; } [self setLocale:en_US_POSIX]; return self; }@end
Instead of subclassing, you could create an NSDateFormatter
category with an additional initializer that takes care of assigning the locale and possibly also a format string, so you'd have a ready-to-use formatter right after initializing it.
@interface NSDateFormatter (LocaleAdditions)- (id)initWithPOSIXLocaleAndFormat:(NSString *)formatString;@end@implementation NSDateFormatter (LocaleAdditions)- (id)initWithPOSIXLocaleAndFormat:(NSString *)formatString { self = [super init]; if (self) { NSLocale *locale = [[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"]; [self setLocale:locale]; [locale release]; [self setFormat:formatString]; } return self;}@end
Then you could use NSDateFormatter
anywhere in your code with just:
NSDateFormatter* fmt = [[NSDateFormatter alloc] initWithPOSIXLocaleAndFormat:@"yyyyMMddHHmmss"];
You might want to prefix your category method somehow to avoid name conflicts, just in case Apple decides to add such a method in a future version of the OS.
In case you're always using the same date format(s), you could also add category methods that return singleton instances with certain configurations (something like +sharedRFC3339DateFormatter
). Be aware however that NSDateFormatter
is not thread-safe and you have to use locks or @synchronized
blocks when you're using the same instance from multiple threads.
May I suggest something totally different because to be honest all of this is somewhat running down a rabbit hole.
You should be using one NSDateFormatter
with dateFormat
set and locale
forced to en_US_POSIX
for receiving dates (from servers/APIs).
Then you should be using a different NSDateFormatter
for the UI which you will set the timeStyle
/dateStyle
properties - this way you're not having an explicit dateFormat
set by yourself, thus falsely assuming that format will be used.
This means UI is driven by user preferences (am/pm vs 24 hour, and date strings formatted correctly to user choice - from iOS settings), whereas dates that are "coming into" your app are always being "parsed" correctly to an NSDate
for you to use.