stringByAppendingString question.

Code:
- (NSMutableString *)parseGameNumbers {

    

    // let's parse the game numbers from the History File and pass them back to the caller as a string.

    

    NSScanner *theScanner;

    NSString *GAMENUMBERID = @"Full Tilt Poker Game #";

    NSCharacterSet *colonSet;

    NSError *error;

    NSString *stringFromFileAtPath = [[NSString alloc] initWithContentsOfFile:historyFile encoding:NSUTF8StringEncoding error:&error];

    NSMutableString *gameNumber;

    NSMutableString *gameNumberList;

    gameNumberList = [NSMutableString alloc];

    

    colonSet = [NSCharacterSet characterSetWithCharactersInString:@":"];

    theScanner = [NSScanner scannerWithString:stringFromFileAtPath];

    

    if (stringFromFileAtPath == nil)

    {

        // an error occurred

        NSLog(@"Error reading file at %@\n%@", historyFile, [error localizedFailureReason]);

    }

    

        while ([theScanner isAtEnd] == NO)

        {

                if ([theScanner scanString:GAMENUMBERID intoString:NULL] && [theScanner scanUpToCharactersFromSet:colonSet intoString:&gameNumber])

        {    

            // we are not getting the game numbers to append here.        

            [gameNumberList stringByAppendingString:gameNumber];

            return gameNumberList;

        }

        

        // else return NO;

    }

    return gameNumberList;

}