title: How to override mutable property from a superclass
body: <pre><code>class ArcaneCardVC: UIViewController {
      var currentCard: ArcaneCardView?
  }
  
  class PostVC: ArcaneCardVC {    
      override var currentCard: PostCard? 
  // &lt;===== This is what I want to do but cant
  }
  
  class ArcaneCardView: UIView {
  
  }
  class PostCard: ArcaneCardView {
  
  }
  </code></pre>
  
  <p>Here is the error I get: </p>
  
  <blockquote>
    <p>Cannot override mutable property 'currentCard' of type 'ArcaneCardView?' with covariant type 'PostCard?'</p>
  </blockquote>
  
  <p>The other solution is explicitly doing this in code everytime I use currentCard:</p>
  
  <pre><code>var card = currentCard as! PostCard
  </code></pre>