메인이 되는 VC를 하나 준비한다.

ViewController

탭에 들어갈 VC들을 미리 준비한다.

FirstVC, SecondVC, ThirdVC 등…

tab 별 아이콘을 준비한다.

ViewController 의 상속 클래스인 UIViewController 를 삭제하고 UITabBarController 로 작성한다.

import UIKit

class ViewController: UITabBarController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        
        // Create Tab one
        let tabOne = FirstVC()
        let tabOneBarItem = UITabBarItem(title: "Tab 1", image: UIImage(named: "Tab1_icon"), selectedImage: UIImage(named: "Tab1_icon"))
        
        tabOne.tabBarItem = tabOneBarItem
        
        
        // Create Tab two
        let tabTwo = SecondVC()
        let tabTwoBarItem2 = UITabBarItem(title: "Tab 2", image: UIImage(named: "Tab2_icon"), selectedImage: UIImage(named: "Tab2_icon"))
        
        tabTwo.tabBarItem = tabTwoBarItem2
        
        
        self.viewControllers = [tabOne, tabTwo]

        self.delegate = self
    }
}

appdelegate.swift 에서 앱의 window에 붙이기

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    
    var window: UIWindow?

    func application(_ application: UIApplication,
                     didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
    ) -> Bool {
        window = UIWindow(frame: UIScreen.main.bounds)
        window?.makeKeyAndVisible()
        
        let tabVC = ViewController()
        window?.rootViewController = tabVC
        
        return true
    }
}

탭 선택 처리하기 UITabBarControllerDelegate

ViewController 상속에 UITabBarControllerDelegate 추가

self.delegate = self

// MARK: - UITabBarControllerDelegate
    override func tabBar(_ tabBar: UITabBar, didSelect item: UITabBarItem) {
        print("didSelect item \(item.tag)")
    }

    func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) {
        
        print(" \(tabBarController.selectedIndex)")
    }

색상 설정

UITabBar.appearance().barTintColor = UIColor(red: 0, green: 0/255, blue: 205/255, alpha: 1)
// or
UITabBar.appearance().barTintColor = UIColor.blue

VC 에서 self.title = “title” 이라고 설정하면 TabBarItem의 텍스트가 자동으로 바뀐다.주의!

scenedelegate 에 바로 박아넣을 때

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 windowScene = (scene as? UIWindowScene) else { return }
        window = UIWindow(windowScene: windowScene)
        
        let tabBarController = UITabBarController()
        
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        
        let homeVC = storyboard.instantiateViewController(identifier: "SB_NAV_HOME") as! UINavigationController
        let settingsVC = storyboard.instantiateViewController(identifier: "SB_NAV_SETTINGS") as! UINavigationController
        
        tabBarController.setViewControllers([homeVC, settingsVC], animated: false)
        
        if let items = tabBarController.tabBar.items {
            items[0].selectedImage = UIImage(systemName: "house.fill")
            items[0].image = UIImage(systemName: "house")
            items[0].title = "HOME".localized
            
            items[1].selectedImage = UIImage(systemName: "gearshape.fill")
            items[1].image = UIImage(systemName: "gearshape")
            items[1].title = "SETTINGS".localized
        }
        
        window?.rootViewController = tabBarController
        window?.makeKeyAndVisible()
        
//        window?.overrideUserInterfaceStyle = .light
    }