ios - unique property in Firebase

Question

I have an IOS app which contains categories. My storage on Firebase looks like this:

-root
   -Categories
      -key
        - color:
        - name:
        - sum:
   -Expenses
      -key
        -amount: 
        -category: 
        -date: 
        -description: 
        -initiator: 
        -name: 

User must not add a category twice. I want to make category name unique. Is it possible to do in Firebase? Thanks in advance.

Answer 1

Waitting for answers