iOS 14 以编程方式创建的 UINavigationController 中不显示导航栏标题

Question

iOS 14.2，当我尝试使用下面的代码片段以编程方式呈现 NavigationController 控制器时。

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

新控制器中的栏标题将不会呈现。我错过了什么吗？

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视图控制器嵌套到 UINavigableController 中，但标题仍未呈现。

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

Answer 1

文档说：

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 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：

Answer 2

@finebel 在 Playground 中的回答

import UIKit
import PlaygroundSupport

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: .touchDown)
        return btn
    }()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        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)
    }
}

// Present the view controller in the Live View window
PlaygroundPage.current.liveView = ViewController()

iOS 14 以编程方式创建的 UINavigationController 中不显示导航栏标题

iOS 14 navigation bar title is not displayed in UINavigationController created programmatically

uikit

ios

swift

ios14