NSDateFormatter not giving me correct

问题

I am displaying time. It will show me :TIME :2012-06-18 23:00:00 +0000 But after using NSDateFormatter I do not know why it is giving me 00:00:00 AM

NSDateFormatter* dateFormatter = [[NSDateFormatter alloc] init];

[dateFormatter setDateFormat:@"HH:mm:ss a"];

NSLog(@"TIME :%@",self.startDate);

NSDate *date = [NSDate date];
NSString * _startTime = [dateFormatter stringFromDate:date];
NSLog(@"current time : %@",_startTime);
NSString * _startTime1 = [dateFormatter stringFromDate:self.startDate];
NSLog(@"Start time : %@",_startTime1);
[dateFormatter release];

**Result is**

TIME :2012-06-18 23:00:00 +0000
current time : 17:05:41 PM
Start time : 00:00:00 AM

回答1:

Your first NSLog outputs the date in GMT time (notice the trailing +0000). An NSDateFormatter object will format the date to the specified time zone. Your NSLog statements show that the stored date in self.startDate is exactly 00:00:00 AM in at least one time zone, and the formatter is set to that time zone. The formatter will default to the time zone for the device. You could set the formatter's timezone to 0 seconds from GMT to see 23:00:00 PM out of your last NSLog statement:

[dateFormatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];

来源：https://stackoverflow.com/questions/11086916/nsdateformatter-not-giving-me-correct