Since, in IPhone development, we can’t use descriptionWithCalendarFormat function to extract different components from NSDate object, there is another way to do that: NSCalendar. If you’re reading this post only for the weekday, so here goes one liner for you (don’t forget that weekday 1 = sunday, not monday like some of us may think):

int weekday = [[[NSCalendar currentCalendar] components:NSWeekdayCalendarUnit fromDate:dateFromString] weekday];

NSCalendar is very useful if you wish to use your elements of date apart from each other. Here is more detailed example how to separate them:

// just some date
NSDate *fooDate = [NSDate date];
// setting units we would like to use in future
unsigned units = NSYearCalendarUnit | NSMonthCalendarUnit |  NSDayCalendarUnit | NSWeekdayCalendarUnit;
// creating NSCalendar object
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
// extracting components from date
NSDateComponents *components = [calendar components:units fromDate:fooDate];

// getting our fooDate components. On at the time. Oh, and they're integers!
[components year];
[components month];
[components day];
[components weekday];

List of all available units:
NSEraCalendarUnit, NSYearCalendarUnit, NSMonthCalendarUnit, NSDayCalendarUnit, NSHourCalendarUnit, NSMinuteCalendarUnit, NSSecondCalendarUnit, NSWeekCalendarUnit, NSWeekdayCalendarUnit, NSWeekdayOrdinalCalendarUnit, NSQuarterCalendarUnit

Tags: iphone-dev, NSCalendar, NSDate, NSDateComponents

This entry was posted on Monday, January 18th, 2010 at 01:11 and is filed under iphone. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.