以编程方式创建的UINavigationController中未显示iOS 14导航栏标题 [英] iOS 14 navigation bar title is not displayed in UINavigationController created programmatically

问题描述

iOS 14.2，当我尝试通过下面的代码片段以编程方式展示NavigationController控制器时.

iOS 14.2, when I tried to present a NavigationController controller programmatically with the code snippet below.

@objc private func handleClick() {
    let viewController = MyViewController()
    
    self.present(viewController, animated: true, completion: nil)
}

新控制器中的条形标题将不会呈现.我想念什么吗?

The bar title in the new controller won't get rendered. Am I missing anything?

class MyViewController: UINavigationController {
    override func viewDidLoad() {
        super.viewDidLoad()

        self.title = "TEST" // NOT WORK
        self.navigationItem.title = "Title" // NOT WORK
    }
}

还尝试了下面的代码片段，将常规的View Controller嵌套到UINavigableController中，但标题仍未呈现.

Also tried the code snippet below to nest a regular View Controller into an UINavigableController but the title is still not rendered.

@objc private func handleHelpClick() {
    let innerVC = MyInnerViewController()
    innerVC.title = "TEST"
    let viewController = UINavigationController(rootViewController: innerVC)
    self.present(viewController, animated: true, completion: nil)
}

推荐答案

文档说:

导航控制器使用与导航堆栈上的视图控制器关联的导航项对象(UINavigationItem类的实例)动态构建导航栏的内容.

A navigation controller builds the contents of the navigation bar dynamically using the navigation item objects (instances of the UINavigationItem class) associated with the view controllers on the navigation stack.

https://developer.apple.com/documentation/uikit/uinavigationcontroller

因此，根据我的理解，您必须为UIViewController本身设置标题，而不是为UINavigationController设置标题.

So from my understanding you have to set the title for your UIViewController itself instead for the UINavigationController.

示例:

class MyViewController: UINavigationController {
    override func viewDidLoad() {
        super.viewDidLoad()
    }
}

class ViewController: UIViewController {
    
    private lazy var button: UIButton = {
        let btn = UIButton()
        btn.translatesAutoresizingMaskIntoConstraints = false
        btn.setTitle("Display NavVC", for: .normal)
        btn.setTitleColor(.blue, for: .normal)
        btn.addTarget(self, action: #selector(displayNavVC), for: .touchUpInside)
        return btn
    }()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .systemBackground
        configureButton()
    }
    
    private func configureButton() {
        view.addSubview(button)
        NSLayoutConstraint.activate([
            button.centerYAnchor.constraint(equalTo: view.centerYAnchor),
            button.centerXAnchor.constraint(equalTo: view.centerXAnchor)
        ])
    }
    
    @objc
    private func displayNavVC() {
        let vc = UIViewController()
        vc.title = "abc"
        let navigationVC = MyViewController(rootViewController: vc)
        
        self.present(navigationVC, animated: true, completion: nil)
    }
}

结果:

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