title: Retrieve firebase data where users root collection references a sibling collection
body: <p>Accessing all maps works perfectly in Firebase with this path, however it grabs all maps available in the "Maps" root collection.</p>
  
  <p><code>let yourMapRef = Database.database().reference().child("Maps")</code></p>
  
  <p>I am trying to only access the maps that the user is part of. I have therefore tried to follow stack questions and firebase tutorials but i cant grasp how to do this.</p>
  
  <p>For example i would like Adam to only grab his moderated maps by </p>
  
  <p><code>let yourMapRef = Database.database().reference().child("users/\(userProfile.uid)/Maps")</code></p>
  
  <p>How should i think around this problem and how can this be solved?</p>
  
  <p><strong>Users</strong> (root collection structure)</p>
  
  <pre><code>{
    "4g99cMTM4begwooORsO4EKNV456" : {
      "username" : "Adam",
      "Maps" : {
        "-LpYo_pQ8zIOGHHlNU1Q" : true
      }
    },
    "6g55cHXH4begwooHQvO4EKNV3xm1" : {
      "username" : "Ellen",
      "Maps" : {
        "-LpY4XEER-b21hwMi9sp" : true
      }
    }
  }
  </code></pre>
  
  <p><strong>Maps</strong> (root collection structure)</p>
  
  <pre><code>{
    "-LpY4XEER-b21hwMi9sp" : {
      "mapmoderators" : {
        "6g55cHXH4begwooHQvO4EKNV3xm1" : true
      },
      "mapphotoURL" : "https://firebasestorage.googleapis.com/v0/b/...",
      "mapusername" : "Hello World"
    },
    "-LpYo_pQ8zIOGHHlNU1Q" : {
      "mapmoderators" : {
        "4g99cMTM4begwooORsO4EKNV456" : true
      },
      "mapphotoURL" : "https://firebasestorage.googleapis.com/v0/...",
      "mapusername" : "Dream"
    }
  }
  </code></pre>