title: Subclassing NSWindowController in Swift and init(windowNibName)
body: <p>I am trying to start a new document based Cocoa project in Swift and want to create a subclass of <code>NSWindowController</code> (as recommended in Apple's guides on document based apps). In ObjC you would make an instance of an <code>NSWindowController</code> subclass sending the <code>initWithWindowNibName:</code> message, which was implemented accordingly, calling the superclasses method.</p>
  
  <p>In Swift <code>init(windowNibName)</code> is only available as an convenience initializer, the designated initializer of <code>NSWindowController</code> is <code>init(window)</code> which obviously wants me to pass in a window.</p>
  
  <p>I cannot call <code>super.init(windowNibName)</code> from my subclass, because it is not the designated initializer, so I obviously have to implement <code>convenience init(windowNibName)</code>, which in turn needs to call <code>self.init(window)</code>. But if all I have is my nib file, how do I access the nib file's window to send to that initializer?</p>