如何将标题/按钮添加到 UIViewController 中添加的 UINavigationController？

Question

由于某种原因，我必须在 UIViewController() 中添加一个 UINavagationController()，所以我在视图控制器类中做了以下操作：

class someViewController: UIViewController {
    private let myNav = UINavigationController()
    override func viewDidLoad() {
        self.addChildViewController(myNav)
        self.view.addSubview(myNav.view)
        myNav.view.translatesAutoresizingMaskIntoConstraints = false
        myNav.view.topAnchor.constraintEqualToAnchor(self.topLayoutGuide.bottomAnchor).active = true
        myNav.view.leftAnchor.constraintEqualToAnchor(view.leftAnchor).active = true
        myNav.view.rightAnchor.constraintEqualToAnchor(view.rightAnchor).active = true
        myNav.view.heightAnchor.constraintEqualToAnchor(nil, constant: 44).active = true
        myNav.didMoveToParentViewController(self)
    }
}

导航控制器已添加并正确显示。然后我尝试向导航栏添加标题（或完成按钮），但是这些项目没有显示出来。我尝试了一些这样的事情：

self.navigationItem.title = "some title"
myNav.navigationItem.title = "some title"
myNav.navigationItem.rightBarButtonItem = btnDone

在这种情况下，正确的做法是什么？

Answer 1

为什么不用这个简单的代码来添加导航栏：

    let navigationBar = UINavigationBar(frame: CGRectMake(0, 0, self.view.frame.size.width, 66)) // Offset by 20 pixels vertically to take the status bar into account


    // Create a navigation item with a title
    let navigationItem = UINavigationItem()
    navigationItem.title = "Title"

    // Create left and right button for navigation item
    let leftButton =  UIBarButtonItem(title: "Save", style:   UIBarButtonItemStyle.Plain, target: self, action: "btn_clicked:")
    let rightButton = UIBarButtonItem(title: "Right", style: UIBarButtonItemStyle.Plain, target: self, action: nil)

    // Create two buttons for the navigation item
    navigationItem.leftBarButtonItem = leftButton
    navigationItem.rightBarButtonItem = rightButton

    // Assign the navigation item to the navigation bar
    navigationBar.items = [navigationItem]

    // Make the navigation bar a subview of the current view controller
    self.view.addSubview(navigationBar)