Курс 2, Урок 55 не отображается панель

#1

Здравствуйте, я новичок в Swift… Скопировал код в свой проект, страничка отображается нормально, но панели с кнопками нет. Пробовал и на реальном устройстве и на эмуляторах. XCode 8.2.1 iOS9.3

import UIKit
import WebKit

class ViewController: UIViewController, WKNavigationDelegate {

var webView: WKWebView!
var progressView: UIProgressView!

deinit {
    webView.removeObserver(self, forKeyPath: #keyPath(WKWebView.estimatedProgress))
}

override func viewDidLoad() {
    super.viewDidLoad()
    
    webView = WKWebView()
    webView.navigationDelegate = self
    view = webView
    
    let url: URL! = URL(string: "https://vk.com")
    let request = URLRequest(url: url)
    webView.load(request)
    webView.allowsBackForwardNavigationGestures = true
    
    progressView = UIProgressView(progressViewStyle: .default)
    progressView.sizeToFit()
    
    let progressButton = UIBarButtonItem(customView: progressView)
    let flexibleSpacer = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)
    let refreshButton = UIBarButtonItem(barButtonSystemItem: .refresh, target: webView, action: #selector(webView.reload))
    
    toolbarItems = [progressButton, flexibleSpacer, refreshButton]
    navigationController?.isToolbarHidden = false
    
    webView.addObserver(self, forKeyPath: #keyPath(WKWebView.estimatedProgress), options: .new, context: nil)
}

override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
    if keyPath == "estimatedProgress" {
        progressView.progress = Float(webView.estimatedProgress)
    }
}

func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
    title = webView.title
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

}