Estimated Weekly Week Index by NSDateComponents

Question

I created a category for NSDate that can create a string representation of a date with the name of the week of the week, like Thursday, January 5th.

I want to get the weekday index and use a custom array of days of the week, which are stored in plist and localized in English and Spanish.

However, using NSDateComponents gives me unexpected results. I request both NSWeekdayOrdinalCalendarUnit and NSWeekdayCalendarUnit , and I logged the results, and I get the following example:

 NSDateComponents *components = [[NSCalendar currentCalendar] components:NSWeekdayOrdinalCalendarUnit | NSWeekdayCalendarUnit fromDate:self]; NSInteger weekdayOrdinal = [components weekdayOrdinal]; NSInteger weekdayNonOrdinal = [components weekday]; NSLog(@"Date: %@", [self description]); NSLog(@"Device oridinal weekday: %d", weekdayOrdinal); NSLog(@"Device non-oridinal weekday: %d", weekdayNonOrdinal); 

2012-01-06 15:05: 56.492 MyApp [964: 11903] Date: 2012-01-05 16:13:46 +0000

2012-01-06 15:05: 56.492 MyApp [964: 11903] Device on the day of the week: 1

2012-01-06 15: 05: 56.493 MyApp [964: 11903] A device without an ordinary weekday: 5

This day should be on Thursday, the serial number should be 4 and not indicate 5

I do not understand where 1 comes from.

I found a way to configure this to make sure we use the gregorian calendar with NSDateFormatter and specifying NSCalendar (with the first date of the week on Monday) as follows:

 NSCalendar *gregorian = [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease]; [gregorian setFirstWeekday:2]; NSUInteger adjustedWeekdayOrdinal = [gregorian ordinalityOfUnit:NSWeekdayCalendarUnit inUnit:NSWeekCalendarUnit forDate:self]; NSDateFormatter *weekdayF = [[[NSDateFormatter alloc] init] autorelease]; [weekdayF setDateFormat: @"EEEE"]; [weekdayF setCalendar:gregorian]; [weekdayF setLocale:[[NSLocale alloc] initWithLocaleIdentifier:@"en_UK"]]; NSLog(@"The day of the week is: %@", [weekdayF stringFromDate:self]); 

This will give me what I want, but now I need to save the locale id in plist for use in Spanish, what I would prefer to save is the first instance with NSDateComponents , but I don’t understand why I sometimes get a funny value .

I found a solution to tune the index using this solution: stack overflow

However, to be honest, I would not want to use this together with NSDateComponents , I would prefer to use NSDateFormatter , but in general it would be great to fix the first example, which gives me a false weekdayOrdinal value.

Any ideas on this?

Answer 1

I think you are misinterpreting what weekdayOrdinal means. According to NSDateComponents , receiving weekdayOrdinal returns the ordinal number of weekday units for the recipient, where the ordinal units of the day of the week are "the position of the day of the week in the next larger calendar block, such as the month., 2 is the ordinal number of the day of the week on the second Friday of the month."

For these reasons, 2012-01-05 correctly has a weekdayOrdinal of 1 b / c on the first Thursday of the month.