SwiftUI - NavigationTitle 在延迟后出现

Question

我试图理解为什么当我将带有 SwiftUI View 的 UIHostingViewController 推送到我的导航堆栈时，当导航标题出现时会有轻微的延迟，正如您从这个演示中看到的那样：

代码：

struct SwiftUIView: View {
  var body: some View {
    EmptyView()
          .navigationTitle("SwiftUI View")
  }
}

与使用标题立即可见的 UIViewController 相比：

我能想到的解决方案之一是在将

.title

推入堆栈之前添加

UIHostingViewController

，但我想知道是否有办法从 SwiftUI 组件修复它？

这是说明我所描述内容的项目：https://github.com/ignotusverum/NavigationTitlesTesting

完整代码：

class ViewController: UIViewController {
    override func loadView() {
        let view = UIView()
        view.backgroundColor = .white
        
        let button = UIButton(type: .system)
        button.addTarget(self,
                         action: #selector(buttonTapped),
                         for: .touchUpInside)
        button.setTitle("Push SwiftUI View", for: .normal)
        
        let button2 = UIButton(type: .system)
        button2.addTarget(self,
                         action: #selector(button2Tapped),
                         for: .touchUpInside)
        button2.setTitle("Push UIViewController", for: .normal)

        let stackView = UIStackView(arrangedSubviews: [button, button2])
        stackView.axis = .vertical
        stackView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(stackView)
        NSLayoutConstraint.activate([
            stackView.heightAnchor.constraint(equalToConstant: 120),
            stackView.centerYAnchor.constraint(equalTo: view.centerYAnchor),
            stackView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            stackView.trailingAnchor.constraint(equalTo: view.trailingAnchor)
        ])
        
        self.view = view
    }
    
    @objc func buttonTapped() {
        let hostingController = UIHostingController(rootView: SwiftUIView())
        
        navigationController?.pushViewController(hostingController,
                                                 animated: true)
    }
    
    @objc func button2Tapped() {
        let viewController = UIViewController()
        viewController.view.backgroundColor = .white
        viewController.title = "UIViewController"
        navigationController?.pushViewController(viewController,
                                                 animated: true)
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        title = "Navigation Test"
        navigationItem.backButtonTitle = "Back"
    }
}

struct SwiftUIView: View {
  var body: some View {
    EmptyView()
          .navigationTitle("SwiftUI View")
  }
}

---

附：

出现这个问题似乎是因为大标题异步更新了它的外观。当 UIHostingController 从 SwiftUI 视图的环境中读取导航标题时会发生延迟。