How to get unique values based on dictionary key, which is an element of an array in objective C ?

Question

How to get unique values based on dictionary key, which is an element of an array in objective C ?

for example:

i am having an array of an Items

aryItem

  aryItem[0] = Dictionary{

               ItemCategory
               ItemName
               ItemPrice

               }

  aryItem[1] = Dictionary{

               ItemCategory
               ItemName
               ItemPrice

               }

   ...........
   ...........
  aryItem[n] = Dictionary{

               ItemCategory
               ItemName
               ItemPrice

               }

Now i want to get only unique ItemCategory , not duplicates. If i can write [[aryItem objectatIndex:i] valueForKey:ItemCategory] i get all categories, same category also included in this. I need only unique categories. I have an option searching whole array and then get unique Itemcategory objects, but i am looking for any short way to accomplish the same thing.

Thanks.

Answer 1

I think NSSet class is most suitable to collect unique values. You can create it using something like:

NSSet* categories = [NSSet setWithArray: [aryItem valueForKey: @"ItemCategory"]];