title: Binding a NSArrayController to a NSPopupButton & NSTextField
body: <p>What I want to accomplish seems like it should be fairly straightforward. I have placed a sample project <a href="https://github.com/ericgorr/arraycontrollerbindings" rel="nofollow noreferrer">here</a>.</p>
  
  <p>I have a NSArrayController filled with an array of NSDictionaries.</p>
  
  <pre><code>[[self controller] addObject:@{ @"name" : @"itemA", @"part" : @"partA" }];
  [[self controller] addObject:@{ @"name" : @"itemB", @"part" : @"partB" }];
  [[self controller] addObject:@{ @"name" : @"itemC", @"part" : @"partC" }];
  </code></pre>
  
  <p>I am populating a NSPopupButton with the items in this array based on the 'name' key. This is easily accomplished with the following bindings </p>
  
  <p><img src="https://i.stack.imgur.com/KyutX.png" alt="bindings"></p>
  
  <p>I would then like to populate a NSTextField with the text in the 'part' key based on the current selection of the NSPopupButton. I have setup the following binding:</p>
  
  <p><img src="https://i.stack.imgur.com/6ygd5.png" alt="textfieldbindings"></p>
  
  <p>With these bindings alone, the text field does display 'partC'.</p>
  
  <p><img src="https://i.stack.imgur.com/shQSx.png" alt="initial display"></p>
  
  <p>However, if I change the value of the NSPopupMenu, what the text field shows does not change.</p>
  
  <p>I thought this would simply be a matter of setting up the 'Selected Object' binding on the NSPopupButton</p>
  
  <p><img src="https://i.stack.imgur.com/pwr4Z.png" alt="selected object"></p>
  
  <p>but that isn't working. I end up with the proxy object in my menu for some strange reason (providing the reason why would be a bonus).</p>
  
  <p><img src="https://i.stack.imgur.com/fcB3G.png" alt="window2"></p>
  
  <p>So, what do I need to do to make this work?</p>