title: How to change the size of a popover
body: <p>I'm having trouble changing the size of my popover presentation. Here is what I have so far</p>
  
  <pre><code> override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) // func for popover
  {
      if segue.identifier == "popoverView"
      {
          let vc = segue.destinationViewController
  
          let controller = vc.popoverPresentationController
  
          if controller != nil
          {
              controller?.delegate = self
              controller?.sourceView = self.view
              controller?.sourceRect = CGRect(x:CGRectGetMidX(self.view.bounds), y: CGRectGetMidY(self.view.bounds),width: 315,height: 230)
              controller?.permittedArrowDirections = UIPopoverArrowDirection(rawValue: 0)
          }
      }
  }
  </code></pre>
  
  <p>So far all this does is center the popover and remove the arrow, which is good. but it doesn't resize the container.  any help would be greatly appreciated. thank you.</p>
  
  <p>when I use preferredContentSize I get the error "Cannot assign to property: 'preferredContentSize' is immutable"</p>