[Xcode 实际操作]三、视图控制器-(4)使用UINavigationController导航栏和工具栏

目录：[Swift]Xcode实际操作

本文将演示如何显示和隐藏导航视图的导航栏和工具栏

打开第一个视图控制器

import UIKit

class FirstSubViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        self.title = "First Page"
        self.view.backgroundColor = UIColor.brown
        self.navigationItem.rightBarButtonItem = UIBarButtonItem(title: "Next", style: UIBarButtonItem.Style.plain, target: self, action: #selector(FirstSubViewController.nextPage))
        
        let imgView = UIImageView(frame: CGRect(x: 0, y: 0,  40, height: 40))
            imgView.image = UIImage(named: "PicRound")
        let view = UIView(frame: CGRect(x: 0, y: 0,  40, height: 40))
        view.backgroundColor = UIColor.purple
        view.addSubview(imgView)
        self.navigationItem.titleView = view
    }
    
    @objc func nextPage()
    {
        let viewController = SecondSubViewController()
        self.navigationController?.pushViewController(viewController, animated: true)
    }

    //首先建立视图控制器声明周期中，视图即将显示的代理方法
    //视图在即将可见时，执行这个方法
    override func viewWillAppear(_ animated: Bool) {
        //先覆盖父类的同名方法
        super.viewWillAppear(animated)
        //显示导航视图控制器的顶部工具栏
        self.navigationController?.setToolbarHidden(false, animated: false)
    }

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

接着编辑第二个视图控制器

在第二个视图控制器中添加两个按钮元素

import UIKit

class SecondSubViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        self.title = "Second Page"
        self.view.backgroundColor = UIColor.purple
        
        //添加一个按钮，当单击这个按钮时，会隐藏导航栏。
        let btHideNavBar = UIButton(frame: CGRect(x: 40, y: 200,  240, height: 30))
        //设置按钮上的标题文字
        btHideNavBar.setTitle("Hide navigation bar", for: UIControl.State())
        //设置按钮的背景颜色为橙色
        btHideNavBar.backgroundColor = UIColor.orange
        //给当前按钮绑定点击事件
        btHideNavBar.addTarget(self, action: #selector(SecondSubViewController.hideNavigatonBar), for: .touchUpInside)
        //然后把按钮，插入到当前视图控制器的根视图
        self.view.addSubview(btHideNavBar)
        
        //使用同样的方法，创建另一个按钮
        //点击这个按钮，会隐藏底部的工具栏
        let btHideToolBar = UIButton(frame: CGRect(x: 40, y: 260,  240, height: 30))
        //设置按钮上的标题文字
        btHideToolBar.setTitle("Hide tool bar", for: UIControl.State())
        //设置按钮的背景颜色为橙色
        btHideToolBar.backgroundColor = UIColor.orange
        //给当前按钮绑定点击事件
        btHideToolBar.addTarget(self, action: #selector(SecondSubViewController.hideToolBar), for: .touchUpInside)
        //然后把按钮，插入到当前视图控制器的根视图
        self.view.addSubview(btHideToolBar)
    }
    
    //创建响应第一个按钮点击事件的方法
    @objc func hideNavigatonBar()
    {
        //当用户点击第一个按钮时，隐藏导航视图控制器的顶部导航栏
        self.navigationController?.setNavigationBarHidden(true, animated: true)
    }

    //接着创建响应第二个按钮的点击事件方法
    @objc func hideToolBar()
    {
        //当用户点击第二个按钮时，隐藏导航视图控制器的顶部工具栏
        self.navigationController?.setToolbarHidden(true, animated: true)
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}