日期处理

NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];NSDate *now;NSDateComponents *comps = [[NSDateComponents alloc] init];NSInteger unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSWeekdayCalendarUnit |                                          NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;now=[NSDate date];comps = [calendar components:unitFlags fromDate:now];week = [comps weekday];    month = [comps month];day = [comps day];hour = [comps hour];min = [comps minute];sec = [comps second];//Week:1 －－星期天2－－星期一3－－星期二4－－星期三5－－星期四6－－星期五7－－星期六