如何在滚动前使导航栏透明(iOS 14)

override func viewDidLoad() {
    super.viewDidLoad()
    
    // 设置导航栏透明
    navigationController?.navigationBar.setBackgroundImage(UIImage(), for: .default)
    navigationController?.navigationBar.shadowImage = UIImage()
    navigationController?.navigationBar.isTranslucent = true
}

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    
    // 隐藏导航栏
    navigationController?.setNavigationBarHidden(true, animated: animated)
}

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)
    
    // 恢复导航栏样式
    navigationController?.setNavigationBarHidden(false, animated: animated)
    navigationController?.navigationBar.setBackgroundImage(nil, for: .default)
    navigationController?.navigationBar.shadowImage = nil
    navigationController?.navigationBar.isTranslucent = false
}