title: Cannot convert value of type '() -> Void' to expected argument type '(() -> Void)?'
body: <p>I am trying to fix my finale error whilst trying to convert to Swift 3, however I am unsure why I am getting the error </p>
  
  <blockquote>
    <p>Cannot convert value of type '() -> Void' to expected argument type '(()
    -> Void)?'</p>
  </blockquote>
  
  <p>For </p>
  
  <pre><code> CATransaction.setCompletionBlock(completion)
  </code></pre>
  
  <p>Complete Function </p>
  
  <pre><code>fileprivate func deleteRowsAtIndexPaths(_ indexPaths: [IndexPath], withRowAnimation animation: UITableViewRowAnimation, duration: TimeInterval, completion:() -&gt; Void) {
      CATransaction.begin()
      CATransaction.setCompletionBlock(completion) //Error
      UIView.animate(withDuration: duration) { () -&gt; Void in
          self.deleteRows(at: indexPaths, with: animation)
      }
      CATransaction.commit()
  }
  </code></pre>
  
  <p>Does anybody know why I am getting this and how I can resolve the error ? </p>