［轉］根據時間(NSDate)獲取具體的信息：月份、星期、天等

[iPhone類代碼]計算時間，month,week and day,hour , minutes and second

//initializtion parameter 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