Question

In our code we do the following:

- (void) createComment:(NSString *)comment ForId:(NSString *)objectId
{    
  [facebookArguments setObject:objectId forKey:FACEBOOK_COMMENTS_FOR_ID_KEY ];
  [facebookArguments setObject:comment forKey:FACEBOOK_COMMENTS_FOR_ID_COMMENT]; 
  [facebookPrefs writeToFile:facebookPrefsFilePath atomically: NO];
  [facebookArguments writeToFile:facebookArgumentsFilePath atomically:NO];
}

but upon calling this code:

NSMutableDictionary* fbArgsDic = [[NSMutableDictionary alloc] initWithContentsOfFile: facebookArgumentsFilePath];
NSLog(@"Dictionary: %@", fbArgsDic);

Here’s the Log output before:

2011-08-04 16:11:53.938 My_App[30909:207] Dictionary: {
    facebookGetCommentsForIdComment = Legend;
    facebookGetCommentsForIdKey = 10150249987646875;
    facebookLikeForIdKey = 10150249445616875;
}

And After:

2011-08-04 16:06:39.685 My_App[30693:207] Dictionary: {
    facebookGetCommentsForIdComment = Legend;
    facebookGetCommentsForIdKey = "1.015024998764688e+16";
    facebookLikeForIdKey = 10150249445616875;
}

It’s converted the FACEBOOK_COMMENTS_FOR_ID_KEY entry, which was a NSString as seen above, into a NSNumber and lost some digits. These are LONG numbers as they are facebook id’s.

Any idea what’s going on and how we can fix it?

Answer 1

The dictionary should be getting serialized as a properly list, which should preserve types. Are you sure id is really an NSString to start with? (Also, I agree with other commenters that you should use a different variable name to avoid confusing with the type id.)

One possibility is that it’s actually an NSDecimalNumber, which gets written out as a numeric type and parsed back in as an NSNumber, losing precision.

Try this:

NSLog(@"Class of id: %@", NSStringFromClass([id class]));

And if it is a numeric type after all, you can do:

[facebookArguments setObject:[id stringValue] forKey:FACEBOOK_COMMENTS_FOR_ID_KEY];