今天要講的是Layout的部分，昨天忘記講到，我會用「MainViewController」去把五個畫面涵蓋在裏面，所以如果是昨天的流程，你在建立五個VC的時候應該還要在建立一個叫做MainViewController，我們會需要MainViewController來當五個畫面的「底」，因為我上篇有說，我們是透過下面的TabBar來做換頁，所以TabBar一定要出現在五個畫面當中，但會有個問題，就是每個畫面如果都做一個TabBar然後像昨天那頁設定，太累了ＱＱ，因此這就是今天的重點！

用一個VC當底，我要換頁的時候，把VC中間那塊UIView換掉就好了！

以下是有包含換頁功能的MainViewController:

//
//  MainViewController.swift
//  FoodDemo
//
//  Created by Wang Allen on 2023/9/15.
//

import UIKit

class MainViewController: BaseViewController {
    
    // MARK: - IBOutlet
    
    @IBOutlet weak var container: UIView!
    @IBOutlet weak var CustomTabBar: CustomTabBar!
    
    // MARK: - Variables
    
    private var homeViewController = HomeViewController()
    private var findingViewController = FindingViewController()
    private var walletViewController = WalletViewController()
    private var newsViewController = NewsViewController()
    private var memberShipViewController = MemberShipViewController()
    var vc: [UIViewController] = []
    var nowVC: Int = BottomItems.HomeViewController.rawValue
    
    // MARK: - LifeCycle
    
    override func viewDidLoad() {
        super.viewDidLoad()
        vc = [homeViewController, findingViewController, walletViewController, newsViewController, memberShipViewController]
//        updateView(0)
        setupNavigationBarStyle(backgroundColor: .black)
        let bell = UIBarButtonItem.addButton(self, action: #selector(popMenuView), imageName: "bell",tintColor: .lightGray)
        let threeLine = UIBarButtonItem.addButton(self, action: #selector(popMenuView), imageName: "menu",tintColor: .lightGray)
        self.navigationItem.rightBarButtonItems = [threeLine, bell]

        CustomTabBar.buttonTapped = {
            let page = $0
            if $0 != self.nowVC {
                self.pageChange(page: $0)
                if page == BottomItems.HomeViewController.rawValue {
                    self.navigationItem.rightBarButtonItems = [threeLine, bell]
                } else if page == BottomItems.FindingViewController.rawValue {
                    self.navigationItem.rightBarButtonItems = [threeLine, bell]

                } else if page == BottomItems.WalletViewController.rawValue {
                    self.navigationItem.rightBarButtonItems = []

                } else if page == BottomItems.NewsViewController.rawValue {

                    self.navigationItem.rightBarButtonItems = []

                } else if page == BottomItems.MemberShipViewController.rawValue {
                    self.navigationItem.rightBarButtonItems = []

                }
            }
        }
    }
    
    // MARK: - UI Settings
    
    @objc func popMenuView() {
        let nextVC = NotificationCenterViewController()
        pushViewController(nextVC, animated: true) {
            print("Enter the Notification Center")

        }
    }
    
    func pageChange(page: Int) {
        self.updateView(page)
    }
    
    private func updateView(_ index: Int) {
        nowVC = index
        if children.first(where: { String(describing: $0.classForCoder) == String(describing: vc[index].classForCoder) }) == nil {
            addChild(vc[index])
            vc[index].view.frame = container.bounds
        }
        container.addSubview(vc[index].view ?? UIView())

        let lbNavTitle = UILabel (frame: CGRect(x: 20, y: 10, width: 320, height: 120))
        lbNavTitle.center = CGPoint(x: 50, y: 0)
        lbNavTitle.text = CustomTabBar.items[index].title
        lbNavTitle.font = UIFont.systemFont(ofSize: 20)
        lbNavTitle.backgroundColor = UIColor.black
        lbNavTitle.textColor = UIColor.lightGray
        lbNavTitle.numberOfLines = 0
        lbNavTitle.textAlignment = .left

    }
    
}

圖包的部分可以去這個網站抓，他是免費商用的：
https://www.iconshock.com/freeicons
成果如下：