title: writeToFile fails on iphone but works on simulator
body: <pre><code>NSString *myfile = [[NSBundle] mainBundle] pathForResource:@"fileName" ofType:@"plist"];    
  NSMutableArray *mydata= [[NSMutableArray alloc] initWithContentsOfFile:myfile];
  
  /* code to modify mydata */
  
  [mydata writeToFile:myfile atomically:YES]
  </code></pre>
  
  <p>In case of simulator 'fileName.plist' is modified but in case of iphone device file remains unchanged. There is no exception seen either.</p>
  
  <p>Is the above code expected to work fine on both iphone and simulator ?</p>
  
  <p>Also in the debugger when I hover over 'mydata' I see different values in case of simulator and device. In case of simulator I see for example, '5 objects' but in case of actual device it shows <code>'{(int)[$VAR count]}'</code>. Could this be related to file not being written ?</p>