【Swift/Apple Watch】ローカル通知機能の実装方法！フォアグラウンド

import UserNotifications

class NotificationManager: NSObject, UNUserNotificationCenterDelegate {
    
    static let shared = NotificationManager()
    
    private override init() {
        super.init()
        // フォアグラウンドでも通知が表示されるようにする
        UNUserNotificationCenter.current().delegate = self
        requestAuthorization()
    }
    
    private func requestAuthorization() {
        let center = UNUserNotificationCenter.current()
        center.requestAuthorization(options: .alert) { granted, error in
            if granted {
                print("許可されました！")
            }else{
                print("拒否されました...")
            }
        }
    }
    
    func scheduleNotification() {
        let content = UNMutableNotificationContent()
        content.title = "通知のタイトル"
        content.body = "通知の本文"

        let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 3, repeats: false)
        let request = UNNotificationRequest(identifier: "uniqueIdentifier", content: content, trigger: trigger)
        UNUserNotificationCenter.current().add(request)
    }
    
    // 通知が表示される際に呼ばれるデリゲートメソッド
    func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
        completionHandler([.banner, .sound, .badge])
    }
}

struct ContentView: View {

    private let notificationManager = NotificationManager.shared

    var body: some View {
        Button {
            notificationManager.scheduleNotification()
        } label: {
            Text("Watch Notify")
        }
    }
}

func userNotificationCenter(
    _ center: UNUserNotificationCenter,
    didReceive response: UNNotificationResponse,
    withCompletionHandler completionHandler: @escaping () -> Void) {
      print("通知をタップされたよ")
      completionHandler()
}