【Xcode/Swift】ローカル通知の出現方法

import UIKit

@main
class AppDelegate: UIResponder, UIApplicationDelegate {
    
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        //追記 -----ここから
        UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .sound]) { (granted, _) in
            if granted {
                UNUserNotificationCenter.current().delegate = self
            }
        }
        //-----ここまで 追記
        return true
    }
    
    // MARK: UISceneSession Lifecycle
    
    func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
        return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
    }
    
    func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {
    }
    
}

//追記 ----ここから
extension AppDelegate: UNUserNotificationCenterDelegate {
    func userNotificationCenter(
        _ center: UNUserNotificationCenter,
        willPresent notification: UNNotification,
        withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
            if #available(iOS 14.0, *) {
                completionHandler([[.banner, .list, .sound]])
            } else {
                completionHandler([[.alert, .sound]])
            }
        }
}
//-----ここまで　追記

import UIKit

class ViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    //アラート画面を表示させる
    private func showNotification() {
        let content = UNMutableNotificationContent()
        content.title = "勉強の時間です"
        content.body = "しっかり集中して取り組みましょう！"
        let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 0.5, repeats: false)
        let request = UNNotificationRequest(identifier: "notification", content: content, trigger: trigger)
        UNUserNotificationCenter.current().add(request)
    }
    
    @IBAction func showAlertAction(_ sender: Any) {
        showNotification()
    }
    
    
}