NSString *stringdata=[NSString stringWithFormat:@"2012-09-28 08:36:29"];
NSDateFormatter *datefor=[[NSDateFormatter alloc]init];
[datefor setDateFormat:@"YYYY-MM-dd HH:mm:ss"];
NSDate *olddate=[datefor dateFromString:stringdata];
NSTimeInterval timezone=[[NSTimeZone systemTimeZone]secondsFromGMT];
NSDate *newdate=[olddate dateByAddingTimeInterval:timezone];
NSDateFormatter *dateformatter=[[NSDateFormatter alloc] init];
[dateformatter setDateFormat:@"YYYY-MM-dd HH:mm:ss"];
NSString * locationString=[dateformatter stringFromDate:newdate];
NSLog(@"oldstring==%@",stringdata);
NSLog(@"newstring==%@",locationString);