title: Add and read a json file in the iPhone app
body: <p>I have created a simple Xcode 4.2 project with a empty view controller.
  I added a json file to this project (i not had a resouces folder/group and so i 
  have create these resouces folder and group).
  So, in my iphone simulator i can read this json file correctly.
  When i have tested my example app on my device I had a error: i can't read the 
  json file: Why?
  I use this simple code lines:</p>
  
  <pre><code>NSString *filePath = [[NSBundle mainBundle] pathForResource:CONFIGURATION_FILE_NAME ofType:CONFIGURATION_FILE_TYEPE]; 
  NSString *jsonString = [[NSString alloc] initWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error: NULL];
  </code></pre>