title: How to perform Realm count query
body: <p>How can I do a count query on Realm?</p>
  
  <p>for example this is my model</p>
  
  <pre><code>class Dog: Object {
    dynamic var name = ""
  }
  class Person: Object {
    dynamic var name = ""
  
    let dogs = List&lt;Dog&gt;()
  }
  </code></pre>
  
  <p>I want to fetch all persons with at least one dog
  something like </p>
  
  <pre><code>Realm().objects(Person).filter("dogs.@count &gt; 0")
  </code></pre>
  
  <p>but @count isn't supported as i understand </p>