本地通知发出声音但不显示(Swift)

import UserNotifications

UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .sound, .badge]) { (granted, error) in
    // 处理授权结果
}

let content = UNMutableNotificationContent()
content.title = "通知标题"
content.body = "通知内容"
content.sound = UNNotificationSound.default

let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 5, repeats: false)

let request = UNNotificationRequest(identifier: "notificationIdentifier", content: content, trigger: trigger)

UNUserNotificationCenter.current().add(request) { (error) in
    // 处理添加通知的结果
}