【Swift UI】アプリアイコンにバッジを付与する方法！applicationIconBadgeNumber

UNUserNotificationCenter.current().requestAuthorization(options: .badge) { (granted, err) in
  // ユーザーに使用許可を申請
}

let application = UIApplication.shared
application.applicationIconBadgeNumber = 5

let application = UIApplication.shared
application.registerUserNotificationSettings(UIUserNotificationSettings(types: [.badge], categories: nil))
application.applicationIconBadgeNumber = 5

extension AppDelegate : UNUserNotificationCenterDelegate {
    
    // フォアグラウンドでも通知が届くようにする
    func userNotificationCenter(
        _ center: UNUserNotificationCenter,
        willPresent notification: UNNotification,
        withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
            // フォアグラウンドに通知が届くたびにバッジを追加する
            incrementBadgeCount()
            completionHandler([[.banner, .list, .sound]])
    }
    
    /// バッジ数を更新する
    private func incrementBadgeCount() {
        // 現在のバッジ数を取得
        let currentBadgeCount = UIApplication.shared.applicationIconBadgeNumber
        // バッジ数を1増やす
        UIApplication.shared.applicationIconBadgeNumber = currentBadgeCount + 1
    }
}

class UNUserNotificationCenter : NSObject

class func current() -> UNUserNotificationCenter

func requestAuthorization(
    options: UNAuthorizationOptions = [],
    completionHandler: @escaping (Bool, Error?) -> Void
)

struct UNAuthorizationOptions {
  static var alert: UNAuthorizationOptions { get }       // アラート
  static var sound: UNAuthorizationOptions { get }       // サウンド
  static var badge: UNAuthorizationOptions { get }       // バッジ
  static var carPlay: UNAuthorizationOptions { get }     // carPlay
  static var provisional: UNAuthorizationOptions { get } // 通知機能のお試し用(通知許可ポップアップは非表示)
}

let center = UNUserNotificationCenter.current()
center.requestAuthorization(options: [.alert, .sound, .badge]) { granted, error in
    if granted {
      print("許可されました！")
    }else{
      print("拒否されました...")
    }
}