title: dataWithContentsOfFile return null
body: <pre><code>NSString *path = dict[@"fileURL"];
  NSData *imageData = [NSData dataWithContentsOfFile:path];
  </code></pre>
  
  <p>imageData is null</p>
  
  <pre><code>dict[@"fileURL"] =
  /var/mobile/Containers/Data/Application/0906AB53-CE1F-45EF-8E00-9D0B7C98956C/Documents/ccc/image/1446625127.png
  </code></pre>
  
  <p>I download the device container and the image did exist.
  What's wrong?</p>