Implement UITabBarController.

	import UIKit

	@UIApplicationMain
	class AppDelegate: UIResponder, UIApplicationDelegate {

	var window: UIWindow?
	var tabBarController: UITabBarController?

	func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

	//tabb
	UITabBar.appearance().tintColor = UIColor.orange
	UITabBar.appearance().unselectedItemTintColor = UIColor.gray
	UITabBar.appearance().barTintColor = .purple
	UITabBar.appearance().isTranslucent = false

	// ページを格納する配列
	var viewControllers: [UIViewController] = []

	let firstViewController: FirstViewController? = FirstViewController()
	firstViewController?.tabBarItem = UITabBarItem(title: "First", image: UIImage(named: "tab-icon-sample"), tag: 1)
	viewControllers.append(firstViewController!)

	let secondViewController: SecondViewController? = SecondViewController()
	secondViewController?.tabBarItem = UITabBarItem(tabBarSystemItem: UITabBarSystemItem.downloads, tag: 2)
	viewControllers.append(secondViewController!)

	let thirdViewController: ThirdViewController? = ThirdViewController()
	thirdViewController?.tabBarItem = UITabBarItem(tabBarSystemItem: UITabBarSystemItem.history, tag: 3)
	viewControllers.append(thirdViewController!)

	tabBarController = UITabBarController()
	tabBarController?.setViewControllers(viewControllers, animated: false)

	self.window = UIWindow(frame: UIScreen.main.bounds)
	self.window!.makeKeyAndVisible()
	window?.rootViewController = tabBarController

	return true
	}

	func applicationWillResignActive(_ application: UIApplication) {
	// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
	// Use this method to pause ongoing tasks, disable timers, and invalidate graphics rendering callbacks. Games should use this method to pause the game.
	}

	func applicationDidEnterBackground(_ application: UIApplication) {
	// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
	// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
	}

	func applicationWillEnterForeground(_ application: UIApplication) {
	// Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
	}

	func applicationDidBecomeActive(_ application: UIApplication) {
	// Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
	}

	func applicationWillTerminate(_ application: UIApplication) {
	// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
	}


	}

view raw AppDelegate.swift hosted with ❤ by GitHub

	import UIKit

	class FirstViewController: UIViewController {

	override func viewDidLoad() {
	super.viewDidLoad()

	self.view.backgroundColor = .green

	let firstViewLabel = UILabel()
	firstViewLabel.frame = self.view.frame
	firstViewLabel.textAlignment = .center
	firstViewLabel.font = UIFont.boldSystemFont(ofSize: 40)
	firstViewLabel.textColor = .black
	firstViewLabel.text = "First View"
	self.view.addSubview(firstViewLabel)
	}
	}

view raw FirstViewController.swift hosted with ❤ by GitHub

	import UIKit

	class SecondViewController: UIViewController {

	override func viewDidLoad() {
	super.viewDidLoad()

	self.view.backgroundColor = .orange

	let firstViewLabel = UILabel()
	firstViewLabel.frame = self.view.frame
	firstViewLabel.textAlignment = .center
	firstViewLabel.font = UIFont.boldSystemFont(ofSize: 40)
	firstViewLabel.textColor = .black
	firstViewLabel.text = "Second View"
	self.view.addSubview(firstViewLabel)
	}
	}

view raw SecondViewController.swift hosted with ❤ by GitHub

	import UIKit

	class ThirdViewController: UIViewController {

	override func viewDidLoad() {
	super.viewDidLoad()

	self.view.backgroundColor = .red

	let firstViewLabel = UILabel()
	firstViewLabel.frame = self.view.frame
	firstViewLabel.textAlignment = .center
	firstViewLabel.font = UIFont.boldSystemFont(ofSize: 40)
	firstViewLabel.textColor = .black
	firstViewLabel.text = "Third View"
	self.view.addSubview(firstViewLabel)

	}
	}

view raw ThirdViewController.swift hosted with ❤ by GitHub