如何在swift 3中编程制作全屏按钮

var fullscreenButton: UIButton!

override func viewDidLoad() {
    super.viewDidLoad()
    
    fullscreenButton = UIButton(type: .system)
    fullscreenButton.frame = CGRect(x: 0, y: 0, width: view.frame.width, height: view.frame.height)
    fullscreenButton.setTitle("全屏", for: .normal)
    fullscreenButton.addTarget(self, action: #selector(fullscreenButtonTapped), for: .touchUpInside)
    
    view.addSubview(fullscreenButton)
}

@objc func fullscreenButtonTapped() {
    if !UIApplication.shared.isStatusBarHidden {
        UIApplication.shared.isStatusBarHidden = true
        navigationController?.setNavigationBarHidden(true, animated: true)
        tabBarController?.tabBar.isHidden = true
    } else {
        UIApplication.shared.isStatusBarHidden = false
        navigationController?.setNavigationBarHidden(false, animated: true)
        tabBarController?.tabBar.isHidden = false
    }
}