NSDateFormatter, am I doing something wrong or is this a bug?

Question

I\'m trying to print out the date in a certain format:

NSDate *today = [[NSDate alloc] init];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init]         


        

Answer 1

Short answer: try [dateFormatter setDateFormat:@"yyyyMMddhhmmss"]; for 12 hour format (note the lowercase hh).

It's been a frustrating topic because so many websites indicate to use HH for hours (including the official Apple documentation), but that sets it to 24 hour format, whereas hh uses 12 hour format. See http://unicode.org/reports/tr35/tr35-6.html#Date_Format_Patterns for more details.

As a bonus, note that you can also use KK or kk for hour of the day format, which will likely be off by one.

Update: I was recently looking at NSLocale (https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSLocale_Class/Reference/Reference.html) and it would seem that you can use autoupdatingCurrentLocale to apply changes made from within the app to the Locale. The upshot of this is that even if the phone is set to use a 24 hour clock (like when you switched to France), you can make a 12/24 toggle for the app that won't impact any other apps on the phone, or require you to leave the app to make the change.