NSDateFormatter and date conversion not working.

Question

I am developing an app for the iPhone where I need to convert an date from an XML feed into just a HH:MM format.

I have the following method that doesn't work and I have no clue what I am doing wrong.

As an example, the timeToConvert string would be: "Mon, 01 Feb 2010 21:55:00 +0100" (without the quotes)

The method works when the region is set to US (I get back the correct date), but not when I change the region (in Settings->General->International) to Spain, or other regions (in that case I get back nil).

- (id)timeConvertToHHMM:(NSString *)timeToConvert {

    NSString *newPubDate = timeToConvert;
    //Let's remove any rubbish from the code
    newPubDate = [newPubDate stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
    //create formatter and format to convert the XML string to an NSDate
    NSDateFormatter *originalDateFormatter = [[[NSDateFormatter alloc] init] autorelease];
    [originalDateFormatter setDateFormat:@"EEE, d MMM yyyy H:mm:ss z"];
    //run the string through the formatter
    NSDate *formattedDate = [[NSDate alloc] init];
    formattedDate = [originalDateFormatter dateFromString:newPubDate];
    //Let's now create another formatter to take the NSDate and convert format it to Hours and minutes
    NSDateFormatter *newDateFormatter = [[[NSDateFormatter alloc] init] autorelease];
    [newDateFormatter setDateFormat:@"HH:mm"]; // 24H clock set
    // And let's convert it back to a readable string
    NSString *calcHHMM = [newDateFormatter stringFromDate:formattedDate];
    NSLog(@"CalcHHMM: %@", calcHHMM);
    return calcHHMM;  
}

Any hint on why this is not working, and just returning NULL will be more than welcome.

Answer 1

Problem appears to be your region setting is not "en-US" so the date formatter doesn't parse the string using the en-US format supplied. Although there may be a more elegant, general solution, doing a setLocale on originalDateFormatter to en_US can be used as a workaround to solve the problem.

As you've already tried in your code:

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