ios - Get random child from Firebase Database

Question

I am trying to use Firebase 3 and Swift 3, to make an app that allows users to create "tests", and the purpose is you're going to be shown a completely random test from the database.

My table:

Users:
- uid
    - email

tests
   - id
      - title
      - user_uid

How do I random select any child from "tests", so I can display them to the user? Should I change my structure somehow?

By this I mean lets say I have this:

tests:
- 12391239123
    - title: "My first test"
    - user_uid: 12312345
- 59696995883
    - title: "Second test"
    - user_uid 12352355

I want to select one of these two objects, so I can display them to the user. And it has to be completely random.

Also is it possible to query the database, so I get all childs where user_uid is equal to the user uid I supply? If so, how?

Answer 1

Waitting for answers