How do you interpret dates with NSDateFormatter?

问题

In the Apple Docs, they say that NSDateFormatter uses the Unicode for spec. I've read the spec, but I'm having troubles interpreting this date:

NSDateFormatter *frm = [[NSDateFormatter alloc] init];
[frm setDateFormat:@"EEE MMM dd HH:mm:ss ZZZ yyyy"];
NSLog(@"Tue Oct 13 09:24:15 +0000 2009 becomes %@", [frm dateFromString:@"Tue Oct 13 09:24:15 +0000 2009"]);

This code prints out:

2009-10-13 11:37:40.334 test2[1704:20b] Tue Oct 13 09:24:15 +0000 2009 becomes (null)

回答1:

Sorry folks, figured it out already. NSDateFormatter defaults to using the current system locale. In the code example above, it only fails if you set your system locale to something other than U.S. To fix it, just before to set the locale to the one used by your date string, like this:

[frm setLocale:[[[NSLocale alloc] initWithLocaleIdentifier:@"en_US"] autorelease]];

来源：https://stackoverflow.com/questions/1559182/how-do-you-interpret-dates-with-nsdateformatter