Not sure this method name accurately describes the behaviour (i.e. you're returning nil and not an empty string). It might be good to create a category on NSDictionary that can handle `NSNull` values. e.g.:
```
@implementation NSDictionary (NullValues)

- (id)objectForKeyNotNull:(id)key
{
    id object = [self objectForKey:key];
    if (object == [NSNull null])
        return nil;
    
    return object;
}

@end
```