display the difference in Days, Hours, Minutes and Seconds with it then updating in realtime?

问题

I am a noob... I have

QuitTime.text = quitDate;

Which is a date in the past... How can I display the difference in Days, Hours, Minutes and Seconds with it then updating in realtime?

回答1:

You can use NSDateComponents

    NSDate *currentDate = [NSDate date];    

    NSCalendar *gregorian = [[[NSCalendar alloc]
                         initWithCalendarIdentifier:NSGregorianCalendar]autorelease];

     NSUInteger unitFlags = NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;

     NSDateComponents *components = [gregorian components:unitFlags
                                            fromDate:quitDate
                                              toDate:currentDate options:0];
     NSLog(@"Component Month:%d",[component month]);
     NSLog(@"Component Day:%d",[component day]);
     NSLog(@"Component Hour:%d",[component hour]);
     NSLog(@"Component Mins:%d",[component minute]);

Reference:Difference between two NSDate objects -- Result also a NSDate

来源：https://stackoverflow.com/questions/13335281/display-the-difference-in-days-hours-minutes-and-seconds-with-it-then-updating