CustomTabBarView(UIKit)

CustomTabBarContainer.swift

import UIKit

extension UINavigationController {
    
    open override func willMove(toParent parent: UIViewController?) {
            
        // 같은 container에 대해 호출된다.
        print("wm, \(title!) | parent: \(String(describing: parent))")
    }
    
    open override func didMove(toParent parent: UIViewController?) {
        
        print("dm, \(title!) | parent: \(String(describing: parent))")
    }
}

class CustomTabBarContainer: UIViewController {
    
    private var viewControllers: [UIViewController] = []
    private var buttons: [UIButton] = []
    
    private lazy var tabBarView: UIView = {
            
        let view = UIView()
            
        view.backgroundColor = .lightGray
            
        return view
    }()
    
    var selectedIndex = 0 {
            willSet {
                // 세팅되기 전에 previewsIndex에 저장
                previewsIndex = selectedIndex
            }
            didSet {
                updateView()
            }
        }
    private var previewsIndex: Int?

    override func viewDidLoad() {
        super.viewDidLoad()
        
        
        setupTabBar()
    }
    
    private func setupTabBar() {
        view.addSubview(tabBarView)
            
        tabBarView.translatesAutoresizingMaskIntoConstraints = false
        
        NSLayoutConstraint.activate([
            tabBarView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
            tabBarView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            tabBarView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            tabBarView.heightAnchor.constraint(equalToConstant: 90)
        ])
        
    }
    
    func setViewControllers(_ viewControllers: [UIViewController]) {

        self.viewControllers = viewControllers
        
        // 🐼🐼
        setupButtons()
        
        // 🙈🙈
        updateView()
    }
    
    // 🐼🐼
    private func setupButtons() {
        
        // 버튼의 넓이는 tab 개수에 맞춰서 유동적으로 변함
        let buttonWidth = view.bounds.width / CGFloat(viewControllers.count)
        
        for (index, viewController) in viewControllers.enumerated() {
            let button = UIButton()
            button.tag = index
            button.setTitle(viewController.title, for: .normal)
            button.setTitleColor(.black, for: .normal)
            
            button.addTarget(self, action: #selector(tabButtonTapped(_:)), for: .touchUpInside)
            tabBarView.addSubview(button)
            
            button.translatesAutoresizingMaskIntoConstraints = false
            NSLayoutConstraint.activate([
                button.bottomAnchor.constraint(equalTo: tabBarView.bottomAnchor),
                button.leadingAnchor.constraint(equalTo: tabBarView.leadingAnchor, constant: CGFloat(index) * buttonWidth),
                button.widthAnchor.constraint(equalToConstant: buttonWidth),
                button.heightAnchor.constraint(equalTo: tabBarView.heightAnchor)
            ])
            
            buttons.append(button)
        }
        
    }
    
    @objc private func tabButtonTapped(_ sender: UIButton) {
        selectedIndex = sender.tag
    }
    
    
    // 🙈🙈
    func updateView() {
        
        if selectedIndex == previewsIndex { return }
        
        // 🦄🦄 이전뷰 삭제
        deleteView()
        
        // 🦅🦅 새로운 뷰 삽입
        setupView()
        
        buttons.forEach { $0.isSelected = ($0.tag == selectedIndex) }
    }
    
    // 🦄🦄 이전뷰 삭제
    private func deleteView() {
        
        guard let prev = previewsIndex else { return }
        
        let previousVC = viewControllers[prev]
        
        previousVC.view.removeFromSuperview()
        
        // ✅ 커스텀 컨테이너 구현시 removeFromParent호출전 willMove를 반드시 호출해야한다.
        previousVC.willMove(toParent: nil)
        
        previousVC.removeFromParent()
        
        // 제거후, didMove를 자동으로 호출
        
    }
    
    // 🦅🦅 새로운 뷰 삽입
    private func setupView() {
        
        let selectedVC = viewControllers[selectedIndex]
        
        // willMove를 자동으로 호출한다.
        
        // 현재 뷰컨트롤러의 자식뷰컨트롤러를 지정하는 경우에 호출된다
        self.addChild(selectedVC)
        
        // ✅ 커스텀 컨테이너 구현시, addChild이후에 반드시 호출해야한다.
        selectedVC.didMove(toParent: self)
        
        view.insertSubview(selectedVC.view, belowSubview: tabBarView)
        
        selectedVC.view.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            selectedVC.view.topAnchor.constraint(equalTo: view.topAnchor),
            selectedVC.view.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -90),
            selectedVC.view.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            selectedVC.view.trailingAnchor.constraint(equalTo: view.trailingAnchor),
        ])
    }
}

SceneDelegate.swift

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

    var window: UIWindow?

    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        // Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
        // If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
        // This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).
        guard let _ = (scene as? UIWindowScene) else { return }
        
        let firstViewController = TestViewController("1")
        firstViewController.view.backgroundColor = .red
        firstViewController.title = "First"
        let firstNavi = UINavigationController(rootViewController: firstViewController)
        
        let secondViewController = TestViewController("2")
        secondViewController.view.backgroundColor = .blue
        secondViewController.title = "Second"
        let secondNavi = UINavigationController(rootViewController: secondViewController)
        
        let thirdViewController = TestViewController("3")
        thirdViewController.view.backgroundColor = .yellow
        thirdViewController.title = "Third"
        let thirdNavi = UINavigationController(rootViewController: thirdViewController)
        
        let customTabBarController = CustomTabBarContainer()
        customTabBarController.setViewControllers([firstNavi, secondNavi, thirdNavi])
        
        window?.rootViewController = customTabBarController
        window?.makeKeyAndVisible()
        
    }
  
    //...
}

TestViewController.swift

import UIKit

final class TestViewController: UIViewController {
    
    var number = ""
    
    let animator = CustomAnimator()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        print("\(number): ViewDidLoad")
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        
        print("\(number): ViewWillAppear")
        
    }
    
    init(_ number: String) {
        super.init(nibName: nil, bundle: nil)
        
        self.number = number
        
        view.layer.borderColor = UIColor.blue.cgColor
        view.layer.borderWidth = 2.0
        
        print("\(number): init")
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    deinit {
        print("\(number): Deinit")
    }
    
    override func willMove(toParent parent: UIViewController?) {
        
        print("\(number) will Move, parent:\(parent)")
    }
    
    override func didMove(toParent parent: UIViewController?) {
        
        print("\(number) did Move, parent:\(parent)")
    }
}