NavigationBarButton没有被隐藏但是在调用viewWillAppear方法时会隐藏它？

Question

func setupRightNavigationItems()
    {
        let menuButton = UIButton(type: .system)
        menuButton.setImage(#imageLiteral(resourceName: "menu-white").withRenderingMode(.alwaysOriginal),for:.normal)
        menuButton.contentMode = .scaleAspectFit
        menuButton.frame = CGRect(x:0,y:0,width:25,height:25)

        let playButton = UIButton(type: .system)
        playButton.setImage(#imageLiteral(resourceName: "nowplaying32").withRenderingMode(.alwaysOriginal), for: .normal)
        playButton.contentMode = .scaleAspectFit
        playButton.frame = CGRect(x:0,y:0,width:25,height:25)

        let nowPlaying = defaults.string(forKey: "NOWPLAYING")
        if nowPlaying == "true"
        {
            playButton.isHidden = false
        }
        else
        {
            playButton.isHidden = true
        }

        menuButton.addTarget(self, action: #selector(menuButtonClicked), for: UIControlEvents.touchUpInside)
        playButton.addTarget(self, action: #selector(notificationPlayButtonClicked), for: UIControlEvents.touchUpInside)

        navigationItem.rightBarButtonItems = [UIBarButtonItem(customView:menuButton),UIBarButtonItem(customView:playButton)]

    }

当我调用此函数时，该按钮变为隐藏，即viewWillAppear中的setupRightNavigationItems，但它不反映按钮在视图中隐藏的变化，当我在检查条件后从另一个函数调用它时请帮助！。

Answer 1

当你想隐藏

时

self.navigationItem.rightBarButtonItem = nil

Answer 2

您的代码运行良好。只是检查你的情况是否正确。

class DemoVC: UIViewController {

    var flag = "true"

    override func viewDidLoad() {
        super.viewDidLoad()

        setupRightNavigationItems()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        flag = "false"
        setupRightNavigationItems()
    }

    @IBAction func onBtnChange(_ sender : UIButton) {
        flag = "true"
        setupRightNavigationItems()
    }

    func setupRightNavigationItems()
    {
        print("called")
        let menuButton = UIButton(type: .system)
        menuButton.setImage(#imageLiteral(resourceName: "likesong").withRenderingMode(.alwaysOriginal),for:.normal)
        menuButton.contentMode = .scaleAspectFit
        menuButton.frame = CGRect(x:0,y:0,width:25,height:25)

        let playButton = UIButton(type: .system)
        playButton.setImage(#imageLiteral(resourceName: "likesong").withRenderingMode(.alwaysOriginal), for: .normal)
        playButton.contentMode = .scaleAspectFit
        playButton.frame = CGRect(x:0,y:0,width:25,height:25)

        let nowPlaying = "true"//defaults.string(forKey: "NOWPLAYING")
        if nowPlaying.lowercased() == flag.lowercased()
        {
            playButton.isHidden = true
        }
        else
        {
            playButton.isHidden = false
        }
        self.navigationItem.rightBarButtonItems = [UIBarButtonItem(customView:menuButton),UIBarButtonItem(customView:playButton)]
    }

}

我从viewDidLoad调用此函数并且正常工作。我只是为测试添加了静态条件。

在touchesBegan按钮上显示，onBtnChange再次隐藏。

试试这个，希望这项工作。

Answer 3

您可以执行以下操作来隐藏和显示导航按钮

<强>隐藏

        self.navigationItem.rightBarButtonItem?.tintColor = .clear
        self.navigationItem.rightBarButtonItem?.isEnabled = false

显示：

    self.navigationItem.rightBarButtonItem?.tintColor = yourbuttonTint color
    self.navigationItem.rightBarButtonItem?.isEnabled = true

Answer 4

你是对的，当从willAppear或didLoad以外的功能调用时，它不会隐藏，因为两个条形按钮项都已创建。你不能简单地隐藏它，

所以在调用此函数之前，请删除rightBarButtonItem，现在每件事都可以。

试试这个，

@IBAction func hideNavigationBar(_ sender: UIButton) {
    navigationItem.rightBarButtonItems = nil
    setupRightNavigationItems()
}

试试这个

    let nowPlaying = defaults.string(forKey: "NOWPLAYING")
    if nowPlaying == "true"
    {
        navigationItem.rightBarButtonItems = [UIBarButtonItem(customView:menuButton),UIBarButtonItem(customView:playButton)]
    }
    else
    {
        navigationItem.rightBarButtonItems = [UIBarButtonItem(customView:menuButton)]
    }

<强>结果：

Answer 5

首先尝试设置nil，然后将按钮设置为刷新视图。

func setupRightNavigationItems() {
    // here your rest code

    // set nil here >>>
    navigationItem.rightBarButtonItems = nil
    navigationItem.rightBarButtonItems = [UIBarButtonItem(customView:menuButton),UIBarButtonItem(customView:playButton)]

}