title: Swift 2 optional guard on string
body: <p>I'm dealing with an issue in swift 2.0 </p>
  
  <p>I get a json file from an API and i'm trying to unwrap some strings out of it.</p>
  
  <p>Sometimes this json gives me a string with the street name of a venue but sometimes not.
  So when i'm trying this</p>
  
  <pre><code>var street = arrRes[indexPath.row]["venueLocation"]!["street"] as! String 
  </code></pre>
  
  <p>It always crashes my app saying it is nil. When i comment it my app runs perfect but it doesnt show the street.
  Any idea of how to unwrap the string without having any issue with <code>nil</code> ??</p>
  
  <p>If tried this code</p>
  
  <pre><code>var street = arrRes[indexPath.row]["venueLocation"]!["street"] as! String 
  
  if street == "" {
     street = "n/a"
  }
  </code></pre>
  
  <p>But it failed also.</p>