title: Can't create a MongoDB Realm Sync in Development Mode
body: <p>I’ve got an iOS (swift) app that’s using a local realm. I’m trying to update it to use a synced realm so eventually I can make my app multi-user and share data. But I am new to MongoDB and Synced Realms.</p>
  <p>I’ve successfully installed/build/run the “TaskTracker” starter “Synced” app on atlas and an iOS client.</p>
  <p>Now I’m trying to make a Synced Realm for my app. I figure I would create a Synced Realm and put it in Development mode from scratch. That way I can convert my existing data into Synced data bit by bit and I don’t have to worry about the server side schema yet. I’m hoping that the schema will be defined for me and I can use it once I’m ready to move to a production level deployment.</p>
  <p>So, I followed the “Get Started with Sync” document (<a href="https://docs.mongodb.com/realm/sync/get-started/" rel="nofollow noreferrer">https://docs.mongodb.com/realm/sync/get-started/</a>). I’ve created my Atlas Cluster (Cluster0), and a Realm app in the web UI. The document says:</p>
  <ol>
  <li>Navigate to the Realm Sync Panel</li>
  <li>Decide whether to use Development Mode (I am).</li>
  <li>Configure Sync:</li>
  </ol>
  <p>In this step in the web UI, it seems that there are 3 steps:</p>
  <ol>
  <li>Select a Cluster to Sync</li>
  <li>Choose a Partition Key</li>
  <li>Define a Database Name</li>
  </ol>
  <p>For Step 1, I can select “Cluster0 - (Service: mongodb-atlas)”</p>
  <p>However in Step 2 is where I get stuck: There is a dropdown that says “Enter a partition key field name…”, but when I select the drop down, it says “No options” and I cannot select anytthing. Therefore I can’t go to the third step or turn dev mode on.</p>
  <p><a href="https://i.stack.imgur.com/mfG4q.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/mfG4q.png" alt="development mode sync setup screen with blocking problem." /></a></p>
  <p>The “Get Started with Sync” document doesn’t say anything about pre-populating the realm with data or schema (I thought that’s why I’m choosing Development Mode, so I can define my data on the fly until I figure out what the schema should be).</p>
  <p>I even went back and created a database in the atlas cluster, but even after creating the database and a collection, the &quot;Choose a Partition Key&quot; dropdown still says &quot;No actions&quot;.</p>
  <p>I’m super stuck here. It’s likely because I don’t understand something. Can someone help me see the light?</p>