title: Difference Between ? and ! in Swift Language?
body: <p>I read a lot of articles online and book (Apple) but I am not able to find out the difference between ? and ! operator in Swift language. </p>
  
  <pre><code>override func tableView(tableView: UITableView!, cellForRowAtIndexPath indexPath: NSIndexPath!) -&gt; UITableViewCell!
      {
  
      }
  
      override func numberOfSectionsInTableView(tableView: UITableView?) -&gt; Int {
          return 1;
      }
  </code></pre>
  
  <p>In the code above the first func declares the tableView as ! and in the second function tableView is declared as ?. </p>