How to get values from repeated JSON keys iOS

Question

I have an app that gathers a users data via JSON. After putting the data into an array, I want to get how many different values occur for a certain key, not how many times is appears.

Example.

I gather restaurant data the user has assembled on a site. His JSON data spits out a key for genre: 6 Pizza places, 4 Chinese places, and 2 Mexican places that he has "liked". So there are 3 different values for the genre key, but they occur x amount of times. I want to be able to see how many different values for genre there are, not how many times they occur, which can get via NSCountedSet once I get the values for genre.

I'm having trouble wrapping my head around how to do this without hard coding in every possibility.

Thanks!

Answer 1

Assuming a format like:

 [
  {
  "Restaurant":"McDonalds",
  "Genre":"Vomit"
  },
  {
  "Restaurant":"Wendys",
  "Genre":"Gross"
  },
  {
  "Restaurant":"Chipotle",
  "Genre":"Delish"
  },
  {
  "Restaurant":"White Castle",
  "Genre":"Gross"
  }
 ]

You could do the following:

NSArray *jsonArray = [NSJSONSerialization JSONObjectWithData:jsonInDataForm options:kNilOptions error:&error];
NSMutableArray *types = [[NSMutableArray alloc] init];
for(NSDictionary *restaurant in jsonArray)
{
    if(![types containsObject:[restaurant objectForKey:@"Genre"]])
        [types addObject:[restaurant objectForKey:@"Genre"]];
}

int numberOfGenres = [types count];