Title: iOS 2011 Alarm Clock Bug
Author: Alex Kirk
Published: January 11, 2011

---

# iOS 2011 Alarm Clock Bug

January 11, 2011

Just to add to the speculation about the causes of the [2011 alarm clock bug of iOS](http://www.macworld.com/article/156793/2011/01/ios_alarm.html)
where the one-time alarms would not activate on January 1 and January 2, 2011.

My guess is that the code that sets off the alarm takes day, month and year into
account when checking whether the alarm should go off. But **instead of using the“
normal” year**, an [ISO-8601 year](http://en.factolex.com/ISO_week_date) could have
been used. This type of year is **calculated by the number of the week** (with Monday
as the first day of the week), thus for the week 52 (from December 27, 2010 to January
2, 2011) the respective year **remains 2010**.

When setting the date to January 1, 2012, the alarm doesn’t go off as well (week
52 of 2011). This adds to my theory and also means that this hasn’t been a one-time
issue and requires a bug fix by Apple.

[Code](https://alex.kirk.at/category/code/), [Observations](https://alex.kirk.at/category/observations/)

Read this next

[Title Junk: Solve it with Javascript](https://alex.kirk.at/2010/12/21/title-junk-solve-it-with-javascript/)

### Leave a Reply 󠀁[Cancel reply](https://alex.kirk.at/2011/01/11/ios-2011-alarm-clock-bug/?output_format=md#respond)󠁿

Only people in [my network](https://alex.kirk.at/friends/) can comment.

This site uses Akismet to reduce spam. [Learn how your comment data is processed.](https://akismet.com/privacy/)