title: How to query nearest users in Firebase with Swift?
body: <p>I want to find nearest users to my location. (For example up to 5km) My nodes in firebase database like below structure,</p>
  
  <pre><code>+ users
    + user_id0
      - latitude: _
      - longitude: _
  </code></pre>
  
  <p>Is there any way getting exact users in that radius. Otherwise I should check each user of them nearest position or not to me using <code>CLLocation distance</code> method.</p>