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Editorial Team
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Asked: 2026-05-26T04:28:47+00:00

I’ve following code snippet which I’m using to deduce the first day of the

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I’ve following code snippet which I’m using to deduce the first day of the week, to display in my calendar view. This code has been working without any issue, till I tested it on iPhone OS 4.3 onwards.

int firstDOW = [m_calendar ordinalityOfUnit:NSWeekdayCalendarUnit inUnit:NSWeekCalendarUnit forDate:fom]%7;

where ‘fom’ is the first date of the month.
When debugged the code, on iOS prior to 4.3, return value for ‘ordinality’ method seems to return correct value( for example if the ‘fom’ date falls on Friday, the value returned from above method is ‘5’). But on iOS >= 4.3, the return value is somehow not the correct weekday( for example, if the ‘fom’ date falls on Friday, the value returned from above method is ‘6’!).
I don’t understand, whether there is any issue with my code, or it really is a bug in the above method.
Has anyone else faced this in iOS >= 4.3??

Thanks and Regards.

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1 Answer

  1. Editorial Team

    I learned a bit more about this method call. It appears that the ordinalityOfUnit:inUnit:forDate: method pays attention to what current locale is and what that locale considers the first day of the week to be.

    For example. In the United States locale the first day of the week is considered to be Sunday while in the Ireland locale, the first day of the week is considered to be Monday.

    If you are in the US locale, and ask for the ordinality of Tuesday, it will return 2 (0 for Sunday, 1 for Monday and 2 for Tuesday). In the Ireland locale, however, it will return 1 (0 for Monday and 1 for Tuesday).

    In short, the ordinality of the day within the week depends on which day is considered to begin the week. In contrast, if you use the NSDateComponents API and get the day of the week from there, you always get a day relative to Sunday === 0. e.g.

    NSDateComponents *components = [[self calendar] components: NSWeekdayCalendarUnit fromDate: [self startingDay]];
NSUInteger weekdayIndex = [components weekday];
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