title: Display UIView below navigation bar in Swift programattically
body: <p>I have a webview that would like to fill up the whole screen only start <em><strong>below the Navigation bar</strong></em> so that the top is visible. By that I don't mean that the view is behind the navigation bar. I mean in the Y-coordinate, its top begins at the bottom of the navigation bar.</p>
  <p>I can get it fill up the screen, however, the top is currently covered by the navigation bar, clipping off the top.</p>
  <p>Right now, I am simply trying to move it down 64 points, the size of the status bar and navigation bar, but my code is crashing when I try to create a frame with a bad instruction error.</p>
  <p>Here is my code:</p>
  <pre><code> let webVew = wkWebView()
      
       override func loadView() {
              
              self.view = webView
          }
          
          override func viewDidAppear(_ animated: Bool) {
              let frame = (frame: CGRect(x: 0, y: (navigationController?.navigationBar.frame.height)! + 20, width: UIScreen.main.bounds.width, height: 40)) as! CGRect  
  //CRASHES on above line with EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)
              
             webView.frame = frame
          } 
  </code></pre>
  <p>How can I get the top of the webview to start at the bottom of the Navigation bar</p>