【Swift】Firebaseからプッシュ通知を受け取るために最低限の実装をする(iOS15対応)

pod 'Firebase/Messaging'

// xxxApp.swift

import SwiftUI
import Firebase
import FirebaseMessaging

class AppDelegate: UIResponder, UIApplicationDelegate {
    func application(_ application: UIApplication,
                     didFinishLaunchingWithOptions
                     launchOptions: [UIApplication.LaunchOptionsKey: Any]? = nil) -> Bool {
        FirebaseApp.configure()
        Messaging.messaging().delegate = self
        UNUserNotificationCenter.current().delegate = self

        // 初回起動時、プッシュ通知の許可ダイアログを表示させる
	let authOptions: UNAuthorizationOptions = [.alert, .badge, .sound]
        UNUserNotificationCenter.current().requestAuthorization(
        options: authOptions,
        completionHandler: { _, _ in }
        )
	
        application.registerForRemoteNotifications()

        return true
    }
}

extension AppDelegate: MessagingDelegate {}

extension AppDelegate: UNUserNotificationCenterDelegate {
    // アプリがフォアグラウンドでプッシュ通知を受信した場合に呼ばれる
    func userNotificationCenter(_ center: UNUserNotificationCenter,
                                willPresent notification: UNNotification,
                                withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
        let userInfo = notification.request.content.userInfo
        print(userInfo)
        completionHandler([.banner, .badge, .sound])
    }

    // 通知センター等でプッシュ通知をタップした場合に呼ばれる
    func userNotificationCenter(_ center: UNUserNotificationCenter,
                                didReceive response: UNNotificationResponse,
                                withCompletionHandler completionHandler: @escaping () -> Void) {
        let userInfo = response.notification.request.content.userInfo
        print(userInfo)
        completionHandler()
    }
}

@main
struct xxxApp: App {
    @UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}