title: Should an outlet to a view controller class be weak or stong? OSX app
body: <p>Here's what i did.</p>
  
  <ol>
  <li>Make a clean OSX project.</li>
  <li>went to main.xib and dragged a popover controller.  This created 2 visible objects on on interface builder.</li>
  <li><p>I went to the appDelegate.h file and did</p>
  
  <p>`-@Property (<strong>assign</strong>) IBOutlet NSViewController *popVC;</p></li>
  <li><p>Then i went to the <code>applicationDidFinishLaunching:</code> method and did</p>
  
  <p>popVC = [[NSViewController alloc] init];</p></li>
  </ol>
  
  <p>Result: I get the following error message:</p>
  
  <p><img src="https://i.stack.imgur.com/swYpY.png" alt="enter image description here"></p>
  
  <p>Shouldnt objects on a nib be weak since it is already owned by the nib?</p>