title: Why did I get a fatal error in Swift? unexpectedly found nil while unwrapping an Optional value
body: <p>I'm gettiing a fatal error and i don't know why. i have tried changing the '!' with '?' at _title but it still don't work.</p>
  <pre><code>class Post: NSObject, NSCoding {
     
      private var _img: String!
      private var _title: String!
      private var _descLbl: String!
      
      var img: String {
          return _img
      }
      
      var titleLbl: String {
          return _title
      }
      
      var descLbl: String {
          return _descLbl
      }
      
      init(imagePath: String, title: String, description: String) {
          self._img = imagePath
          self._title = title
          self._descLbl = description
      }
  }
  </code></pre>
  <p>Here is where i get the error:</p>
  <blockquote>
  <p>fatal error: unexpectedly found nil while unwrapping an Optional value</p>
  </blockquote>
  <pre><code>class PostCell: UITableViewCell {
  
      @IBOutlet weak var postImg: UIImageView!
      @IBOutlet weak var title: UILabel!
      @IBOutlet weak var descLbl: UILabel!
      
      
      override func awakeFromNib() {
          super.awakeFromNib()
          // Initialization code
      }
      
      func configureCell(post: Post) {
          title.text = post.titleLbl //Here i get the error
          descLbl.text = post.descLbl
      }
  }
  </code></pre>
  <p>Here i call the function configureCell in ViewController:</p>
  <pre><code>func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -&gt; UITableViewCell {
      let post = posts[indexPath.row]
      
      if let cell = tableView.dequeueReusableCellWithIdentifier(&quot;postCell&quot;) as? PostCell {
          cell.configureCell(post)
          return cell
      }else{
          var cell = PostCell()
          cell.configureCell(post)
          return cell
      }
  }
  </code></pre>