Question

I use the following code to create an NSDate from string:

NSDateFormatter *df = [[[NSDateFormatter alloc] init] autorelease];
[df setTimeZone:[NSTimeZone defaultTimeZone]];
[df setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
NSLog(@"The date from string: %@", [df dateFromString:@"2012-01-31 01:32:30"]);

What I see in the result is:

The date from string: 2012-01-31 07:32:30 +0000

This is obviously not correct.
Do you know why it adds 6 hours to my result date and how to fix it?

Answer 1

NSLog of dates is not a good way to display dates with time zones, instead use an NSDateFormatter to get a string for the time zone desired.

NSDate is UTC based, the one true time that can be correctly displayed for any timezone with NSDateFormatter.

From the Apple NSDate docs:

To parse strings containing dates and to generate string
representations of a date, you should use an instance of
NSDateFormatter using the methods dateFromString: and stringFromDate:
respectively—see “Date Formatters” for more details.

Example code:

NSDateFormatter *df = [[NSDateFormatter alloc] init];
[df setTimeZone:[NSTimeZone defaultTimeZone]];
[df setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
NSDate *date = [df dateFromString:@"2012-01-31 01:32:30"];
NSLog(@"The date from string: %@", date);

NSString *stringFromDate = [df stringFromDate:date];
NSLog(@"stringFromDate: %@", stringFromDate);

NSLog output:

The date from string: 2012-01-31 06:32:30 +0000
stringFromDate: 2012-01-31 01:32:30