[iPhone] NavigationController の設定

UINavigationControllerを使うと複数のViewControllerを階層的に管理できます。
下の例はストーリーボードを使わずに3つのViewControllerをBarButtonを使って遷移させています。

Swift 5
Xcode 10.2.1

UINavigationController

Segueで画面遷移のようにしてもいいのですがUINavigationControllerをつかうとスマートにできるケースもあります。

PreviousView

ViewController

NextView

ページ上にある barButtonSystemItem を使って前のページ、次のページとページ変更が簡単にできます。

目次
1. ViewControllerの追加準備
2. サンプルコード

ViewControllerの追加準備

2つのViewControllerをつかで作ります
それぞれの遷移は

PreviousViewController
NextViewController

とします。

新しいViewControllerはstoryboardに追加するのと合わせて「New File..」から「Cocoa Touch Class」を作成する必要があります。↓を参考にしてください

[iPhone] Segueで画面遷移させる

アプリでA画面からB画面に遷移したいケースは結構あります。コードで記述せざる得ない場合もありますが、StoryboardでSceneを作って…

storyboardにはこのケースでは何もしません

barButtonSystemItem を使うと遷移先の設定がいらないので簡単なのですが
イメージ的に左ボタンで移動した画面は右ボタンで戻るようにしてみました

サンプルコード

AppDelegate にViewController を rootViewController として設定して UINavigationControllerを設置します。

AppDelegate.swift

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    var navigationController: UINavigationController?

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

        let viewController: ViewController = ViewController()

        navigationController = UINavigationController(rootViewController: viewController)

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

        return true
    }

…
}

import UIKit

@UIApplicationMain

class AppDelegate: UIResponder, UIApplicationDelegate {

var window: UIWindow?

var navigationController: UINavigationController?

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

let viewController: ViewController = ViewController()

navigationController = UINavigationController(rootViewController: viewController)

self.window = UIWindow(frame: UIScreen.main.bounds)

self.window?.rootViewController = navigationController

self.window?.makeKeyAndVisible()

return true

}

…

}

ViewController.swift

import UIKit

class ViewController: UIViewController {

    // ボタンを用意
    var leftBarButton: UIBarButtonItem!
    var rightBarButton: UIBarButtonItem!

    override func viewDidLoad() {
        super.viewDidLoad()

        self.navigationItem.title = "Top Page"

        leftBarButton = UIBarButtonItem(title: "< Previous", style: .plain, target: self, action: #selector(ViewController.tappedLeftBarButton))

        rightBarButton = UIBarButtonItem(title: "Next >", style: .plain, target: self, action: #selector(ViewController.tappedRightBarButton))

        self.navigationItem.leftBarButtonItem = leftBarButton
        self.navigationItem.rightBarButtonItem = rightBarButton

        self.view.backgroundColor = UIColor.white
    }

    // ボタンをタップしたときのアクション
    @objc func tappedLeftBarButton() {
        let previousPage = PreviousViewController()
        self.navigationController?.pushViewController(previousPage, animated: true)
    }

    // ボタンをタップしたときのアクション
    @objc func tappedRightBarButton() {
        let nextPage = NextViewController()
        self.navigationController?.pushViewController(nextPage, animated: true)
    }

}

import UIKit

class ViewController: UIViewController {

// ボタンを用意

var leftBarButton: UIBarButtonItem!

var rightBarButton: UIBarButtonItem!

override func viewDidLoad() {

super.viewDidLoad()

self.navigationItem.title = "Top Page"

leftBarButton = UIBarButtonItem(title: "< Previous", style: .plain, target: self, action: #selector(ViewController.tappedLeftBarButton))

rightBarButton = UIBarButtonItem(title: "Next >", style: .plain, target: self, action: #selector(ViewController.tappedRightBarButton))

self.navigationItem.leftBarButtonItem = leftBarButton

self.navigationItem.rightBarButtonItem = rightBarButton

self.view.backgroundColor = UIColor.white

}

// ボタンをタップしたときのアクション

@objc func tappedLeftBarButton() {

let previousPage = PreviousViewController()

self.navigationController?.pushViewController(previousPage, animated: true)

}

// ボタンをタップしたときのアクション

@objc func tappedRightBarButton() {

let nextPage = NextViewController()

self.navigationController?.pushViewController(nextPage, animated: true)

}

NextViewController.swift

import UIKit

class NextViewController: UIViewController {

    var leftBarButton: UIBarButtonItem!
    var rightBarButton: UIBarButtonItem!

    override func viewDidLoad() {
        super.viewDidLoad()

        self.navigationItem.title = "Next Page"

        leftBarButton = UIBarButtonItem(title: "< Top Page", style: .plain, target: self, action: #selector(NextViewController.tappedLeftBarButton))

        rightBarButton = UIBarButtonItem(title: "", style: .plain, target: self, action: #selector(NextViewController.NoAction))

        self.navigationItem.leftBarButtonItem = leftBarButton
        self.navigationItem.rightBarButtonItem = rightBarButton

        self.view.backgroundColor = UIColor.blue
    }

    // ボタンをタップしたときのアクション
    @objc func tappedLeftBarButton() {
        let topPage = ViewController()
        self.navigationController?.pushViewController(topPage, animated: true)
    }

    @objc func NoAction(){
        // nothing to do
    }

}

import UIKit

class NextViewController: UIViewController {

var leftBarButton: UIBarButtonItem!

var rightBarButton: UIBarButtonItem!

override func viewDidLoad() {

super.viewDidLoad()

self.navigationItem.title = "Next Page"

leftBarButton = UIBarButtonItem(title: "< Top Page", style: .plain, target: self, action: #selector(NextViewController.tappedLeftBarButton))

rightBarButton = UIBarButtonItem(title: "", style: .plain, target: self, action: #selector(NextViewController.NoAction))

self.navigationItem.leftBarButtonItem = leftBarButton

self.navigationItem.rightBarButtonItem = rightBarButton

self.view.backgroundColor = UIColor.blue

}

// ボタンをタップしたときのアクション

@objc func tappedLeftBarButton() {

let topPage = ViewController()

self.navigationController?.pushViewController(topPage, animated: true)

}

@objc func NoAction(){

// nothing to do

}

PreviousViewController.swft

import UIKit

class PreviousViewController: UIViewController {

    var leftBarButton: UIBarButtonItem!
    var rightBarButton: UIBarButtonItem!

    override func viewDidLoad() {
        super.viewDidLoad()

        self.navigationItem.title = "Previous Page"

        leftBarButton = UIBarButtonItem(title: "", style: .plain, target: self, action: #selector(PreviousViewController.NoAction))

        rightBarButton = UIBarButtonItem(title: "Top Page >", style: .plain, target: self, action: #selector(PreviousViewController.tappedRightBarButton))

        self.navigationItem.leftBarButtonItem = leftBarButton
        self.navigationItem.rightBarButtonItem = rightBarButton

        self.view.backgroundColor = UIColor.green
    }

    // ボタンをタップしたときのアクション
    @objc func tappedRightBarButton() {
        let topPage = ViewController()
        self.navigationController?.pushViewController(topPage, animated: true)
    }

    @objc func NoAction(){
        // nothing to do
    }

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

}

import UIKit

class PreviousViewController: UIViewController {

var leftBarButton: UIBarButtonItem!

var rightBarButton: UIBarButtonItem!

override func viewDidLoad() {

super.viewDidLoad()

self.navigationItem.title = "Previous Page"

leftBarButton = UIBarButtonItem(title: "", style: .plain, target: self, action: #selector(PreviousViewController.NoAction))

rightBarButton = UIBarButtonItem(title: "Top Page >", style: .plain, target: self, action: #selector(PreviousViewController.tappedRightBarButton))

self.navigationItem.leftBarButtonItem = leftBarButton

self.navigationItem.rightBarButtonItem = rightBarButton

self.view.backgroundColor = UIColor.green

}

// ボタンをタップしたときのアクション

@objc func tappedRightBarButton() {

let topPage = ViewController()

self.navigationController?.pushViewController(topPage, animated: true)

}

@objc func NoAction(){

// nothing to do

}

override func didReceiveMemoryWarning() {

super.didReceiveMemoryWarning()

// Dispose of any resources that can be recreated.

}

PreviousViewControllerでは
システムボタンがデフォルトで表示されるのを
あえて隠すようにしました