iphone - 如何找到一个月的特定日期？

Question

我对 NSDate NSDateFormatter 和 NSCalendar 做了很多研究，但无法找到一种方法来找到特定的一天月。 例如， 我想查找 12 月的第二个星期一的日期 (10/12/2012)。我知道如何找到周数或月数，但不知道如何做。

谢谢。

Answer 1

    // Set start date of the month you want
    NSString *str = @"01 - 12 - 2012";
    NSDateFormatter *formatter1 = [[[NSDateFormatter alloc] init] autorelease];
    [formatter1 setDateFormat:@"dd - MM - yyyy"];
    NSDate *date = [formatter1 dateFromString:str];
    NSCalendar *gregorian = [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease];
    NSDateComponents *weekdayComponents = [gregorian components:(NSDayCalendarUnit | NSWeekdayCalendarUnit) fromDate:date];
    // Get the weekday with sunday as one
    NSInteger weekday = [weekdayComponents weekday];
    int weekNumber = 2;
    int dayOfweek = 2;
    int x = (7 - weekday) * (weekNumber - 1) + dayOfweek;
    // Add the no. of weeks - 1 or - 2 depending on the value of x.
    // Also Add 1 as the start date is 1st Dec.
    if(x < 7)
    {
        x += 7 * (weekNumber - 1) + 1;
    }
    else
    {
        x += 7 * (weekNumber - 2) + 1;
    }