title: valueForKey does not return the right value
body: <p>in my App there is a NSDictionary called "selectedItems" and it contains the key "Order". The value can be changed by the User.
  The definition of the NSDictionary lokks like this:</p>
  
  <pre><code>self.selectedItems = [NSMutableDictionary dictionaryWithObjects:@[self.choosedAttributes, @"Reihennfolge"] forKeys:@[@"Sorted by" ,@"Order"]];
  </code></pre>
  
  <p>I need to set a BOOL Value and I can easily set the Value like this</p>
  
  <pre><code>[self.selectedItems setValue:[NSNumber numberWithBool:NO] forKey:@"Order"];
  </code></pre>
  
  <p>After this operation the value is tranfered to an other ViewController, where i want to read the value.</p>
  
  <pre><code>NSSortDescriptor *mySortDesc = [[NSSortDescriptor alloc] initWithKey:@"firstName" ascending:(Boolean)[stvc.selectedItems valueForKey:@"Order"]];
  </code></pre>
  
  <p>This failed. The Value [stcv.selectedItems valueForKey:@"Order"] is the right one (a NSLog tells me that) But theres no effect on the GUI (ordering Persons by Name ascending or descending). But if i type a static Number or a constant like YES or NO.... it works. But the value is really the same. and this does not work. Can anybody help me please?</p>