If you are one of the lucky iOS 6 users taking advantage of the Do Not Disturb feature on your iPhone, iPad or iPod Touch, you will notice that it no longer functions properly after New Years. With the feature stuck on rather than turning off automatically, Apple has issued a support document stating that it will resume functioning normally after January 7th 2013, which leads us to believe that this is not a software glitch which will get patched automagically, but actually a bug in the way Apple is calculating dates on iOS.
Here's how it works and why it's throwing DND for a loop. The ISO week numbering system uses the YYYY format for the year instead of the Gregorian calendar's yyyy. It then looks at which week of the year it is, and then uses a date digit with 1 starting on Monday. So, for example, Tuesday of the 50th week of 2012 would have been 2012-W50-2 in ISO week format.
The problem comes in when January 1 of the new year ends up falling on a date that doesn't get along well with the ISO week format. The first day of 2013 started on a Tuesday, whereas (as noted by TUAW) the ISO standard expects the first week of the year to start on "the Monday that contains the first Thursday in January." In this case, that would be January 7, 2013.
But you got to love the timing that this ad aired:
And if anyone is writing out there that "Apple will fix this on January 7", Apple will do absolutely nothing but wait, the real fix will be in their next update for iOS.