NSDate NSFormatter NSCalender 的使用

 [fmt setDateFormat:@"yyyy/MM/dd hh:mm:ss:SSS"];
  NSString *string=[fmt stringFromDate:nsDate];

 

 NSDateFormatter *dateFormatter = [[[NSDateFormatteralloc] init] autorelease];

    [dateFormatter setDateFormat:@"yyyyMMddhhmmssSSS"];

    return [dateFormatter stringFromDate:[NSDate date]];

 

 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];  
int year=[comps year];  
int week = [comps weekday];     
int month = [comps month];  
int day = [comps day];  
int hour = [comps hour];  
int min = [comps minute];  
int sec = [comps second];