title: NSUTF8StringEncoding returns nil NSString
body: <p>I'm developing an iOs 4 application with latest SDK and XCode 4.2.</p>
  
  <p>I'm using a web service to retrieve some data, and I receive that data. But, when I do this </p>
  
  <pre><code>NSString *json_string = [[NSString alloc] initWithData:receivedData encoding:NSUTF8StringEncoding];
  </code></pre>
  
  <p><code>receivedData</code> has 944bytes but <code>json_string</code> is nil.</p>
  
  <p>From web service I'm getting this string (copy &amp; pasted from browser window):</p>
  
  <pre><code>{"posts": [ { "ID": "324","fecha": "10/02/2012","titulo": "Preparada para la lluvia","texto": "¡Al mal tiempo buena cara! Eso pensÃ© al vestirme el otro dÃ­a que hiz...","foto": "2012/02/image20.jpg" } ] }
  </code></pre>
  
  <p>I have tried to validate JSON here, <a href="http://jsonformatter.curiousconcept.com/" rel="noreferrer">http://jsonformatter.curiousconcept.com/</a>, but I get it is invalid. Show me this formatted output:</p>
  
  <pre><code>{
     "posts":[
        {
           "ID":"324",
           "fecha":"10/02/2012",
           "titulo":"Preparada para la lluvia",
           "texto":,
           "foto":"2012/02/image20.jpg"
        }
     ]
  }
  </code></pre>
  
  <p>And this errors:</p>
  
  <pre><code>Error:Strings should be wrapped in double quotes.[Code 17, Structure 20]
  Error:Invalid characters found.[Code 18, Structure 20]
  </code></pre>
  
  <p>Any clue about what is happening?</p>