title: NSFileHandle readInBackgroundAndNotify does not work
body: <p>Hi I'm using NSFileHandle's readInBackgroundAndNotify method to get notifications when a log file has been updated.</p>
  
  <p>I have the following code:</p>
  
  <pre><code>- (void)startReading
  {
      NSString *logPath = [NSHomeDirectory() stringByAppendingPathComponent:@"Library/Logs/MyTestApp.log"];
      NSFileHandle *fh = [NSFileHandle fileHandleForReadingAtPath:logPath];
      NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];
      [notificationCenter addObserver:self
                             selector:@selector(getData:)
                                 name:NSFileHandleReadCompletionNotification
                               object:fh];
      [fh readInBackgroundAndNotify];
  }
  
  - (void) getData: (NSNotification *)aNotification
  {
       NSLog(@"notification received");
  }
  </code></pre>
  
  <p>However the selector is never called and the notification is not received.</p>