An NSDate Category With Locale-Aware Calculations for Beginning & End of Day, Week, Month, and Year

Thompson's Law: Any code that performs sufficiently complex date calculations using naïve arithmetic means has a non-zero chance of causing a Y2K-style collapse of the global technology infrastructure.

If your code defines kSecondsInDay, kSecondsInWeek--or worst of all--kSecondsInMonth (seriously, what would you set for that?)... you may want to reconsider. Date and time systems are really, really complicated. Between all of the time zones, calendars and other locale-specific information you should be prepared for, you really can't get it right yourself.

Thank $DEITY for NSCalendar is all I'm saying. Anyway, this library uses NSCalendar and NSDateComponents exclusively for date calculation, so you'll handle everything from leap years to leap months like a champ.

NSLog(@"Current Time: %@", date);
NSLog(@"Beginning of Day:%@", [date beginningOfDay]);
NSLog(@"End of Day:%@", [date endOfDay]);
NSLog(@"Beginning of Week:%@", [date beginningOfWeek]);
NSLog(@"End of Week:%@", [date endOfWeek]);
NSLog(@"Beginning of Month:%@", [date beginningOfMonth]);
NSLog(@"End of Month:%@", [date endOfMonth]);
NSLog(@"Beginning of Year:%@", [date beginningOfYear]);
NSLog(@"End of Year:%@", [date endOfYear]);

Result (Note the Time Zone and Daylight Savings Offsets)

Current Time: 2013-10-19 13:29:26 +0000
Beginning of Day: 2013-10-18 22:00:00 +0000
End of Day: 2013-10-19 21:59:59 +0000
Beginning of Week: 2013-10-12 22:00:00 +0000
End of Week: 2013-10-19 21:59:59 +0000
Beginning of Month: 2013-09-30 22:00:00 +0000
End of Month: 2013-10-31 22:59:59 +0000
Beginning of Year: 2012-12-31 23:00:00 +0000
End of Year: 2013-12-31 22:59:59 +0000

Mattt Thompson

• http://github.com/mattt
• http://twitter.com/mattt
• [email protected]

"A Cupertino Yankee in Scott Forstall's Court" is available under the MIT license. See the LICENSE file for more info.