NSDate *date = [NSDate date];
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *comps;
// 年月日获得
comps = [calendar components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit)
fromDate:date];
// NSInteger year = [comps year];
// NSInteger month = [comps month];
// NSInteger day = [comps day];
// NSLog(@"year: %d month: %d, day: %d", year, month, day);
//当前的时分秒获得
// comps = [calendar components:(NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit)
// fromDate:date];
// NSInteger hour = [comps hour];
// NSInteger minute = [comps minute];
// NSInteger second = [comps second];
// NSLog(@"hour: %d minute: %d second: %d", hour, minute, second);
comps = [calendar components:(NSWeekCalendarUnit | NSWeekdayCalendarUnit | NSWeekdayOrdinalCalendarUnit)
fromDate:date];
// NSInteger week = [comps week]; // 今年的第几周
NSInteger weekday = [comps weekday]; // 星期几（注意，周日是“1”，周一是“2”。。。。）
// NSInteger weekdayOrdinal = [comps weekdayOrdinal]; // 这个月的第几周
