日历NSCalendar

日历

• 某一天
  - (NSInteger)day:(NSDate *)date{
  NSDateComponents *components = [[NSCalendar currentCalendar] components:(NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:date];
  return [components day];
  }

• 某一月
  - (NSInteger)month:(NSDate *)date{
  NSDateComponents *components = [[NSCalendar currentCalendar] components:(NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:date];
  return [components month];
  }

• 某一年
  - (NSInteger)year:(NSDate *)date{
  NSDateComponents *components = [[NSCalendar currentCalendar] components:(NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:date];
  return [components year];
  }

• 某月第一天是周几
  - (NSInteger)firstWeekdayInThisMonth:(NSDate *)date{
  NSCalendar *calendar = [NSCalendar currentCalendar];

      [calendar setFirstWeekday:1];//1.Sun. 2.Mon. 3.Thes. 4.Wed. 5.Thur. 6.Fri. 7.Sat.
      NSDateComponents *comp = [calendar components:(NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:date];
      [comp setDay:1];
      NSDate *firstDayOfMonthDate = [calendar dateFromComponents:comp];
  
      NSUInteger firstWeekday = [calendar ordinalityOfUnit:NSCalendarUnitWeekday inUnit:NSCalendarUnitWeekOfMonth forDate:firstDayOfMonthDate];
      return firstWeekday - 1;
  }
  

• 某个月有多少天
  - (NSInteger)totaldaysInMonth:(NSDate *)date {
  NSRange daysInLastMonth = [[NSCalendar currentCalendar] rangeOfUnit:NSCalendarUnitDay inUnit:NSCalendarUnitMonth forDate:date];
  return daysInLastMonth.length;
  }
  [Demo地址]（https://github.com/haidumou/Calendar.git）