title: NSNumber numberWithBool not an objective-c object
body: <p>I'm need to store some bool values in NSMutableDictionary, so I've founded a solution: using a [NSNumber numberWithBool] to make an object from bool.
  It's work fine with value YES, but with NO it sometimes work fine, and sometimes result is "Not an objective-c object".
  MyCode:</p>
  
  <pre><code>$ //sometimes fine, but sometimes "not an objective-c object"
  $ NSNumber* nsn = [NSNumber numberWithBool:NO];
  </code></pre>
  
  <p>I'm new to Objective-C, so i'm sorry if this is basic problem, but i really stuck with it.
  Thanks for help.</p>