title: Realm Iterator Exception for method iterator.next()
body: <p>I have a Realm Object called Person which contains a reference to a List, where Dog is another Realm Object.</p>
  
  <p>In order to traverse this list of dogs, I store an iterator using the following code (iterator and currentDog are defined within the ViewController)</p>
  
  <pre><code>iterator = selectedPerson.dogs.makeIterator() // dogs: List&lt;Dog&gt;
  currentDog = iterator.next()
  </code></pre>
  
  <p>This performs works as necessary.</p>
  
  <p>However, when trying to update currentDog from another function using the following code, I end up with an exception thrown by the RLMIterator class: EXC_BAD_ACCESS.</p>
  
  <pre><code>if currentDogNumber &lt; selectedPerson.dogs.count {
      currentDog = iterator.next()
  }
  </code></pre>
  
  <p>UPDATE:</p>
  
  <p>I no longer receive any errors if I change the second code snippet to the following rather crude code snippet:</p>
  
  <pre><code>if currentDogNumber &lt; selectedPerson.dogs.count {
      iterator = selectedPerson.dogs.makeIterator()
      for _ in 0...currentDogNumber {
          currentDog = interval.next()
      }
  }
  </code></pre>
  
  <p>Could this be due to the methods being executed on separate threads? 
  And if so, how do I ensure that they are executed by the same thread</p>