[Xcode10 实际操作]三、视图控制器-(6)UINavigationController导航栏样式

本文将演示对导航栏进行样式设置，以及更改导航顶部的提示区。

选择编辑第一个视图控制器文件。

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))
    }
    
    @objc func nextPage()
    {
        let viewController = SecondSubViewController()
        self.navigationController?.pushViewController(viewController, animated: true)
    }

    //建立视图控制器对象的生命周期中的，视图即将显示的代理方法。
    //视图在即将显示时，，执行这个方法
    override func viewWillAppear(_ animated: Bool) {
        //首先实现父类的同名方法
        super.viewWillAppear(animated)
        //设置顶部导航区的提示文字
        self.navigationItem.prompt = "Loading..."
        //设置导航栏的背景是否透明
        self.navigationController?.navigationBar.isTranslucent = false
        //设置导航栏的系统样式
        self.navigationController?.navigationBar.barStyle = UIBarStyle.black
        //设置导航栏的前景颜色。
        self.navigationController?.navigationBar.tintColor = UIColor.orange
    }

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