APNs

// NotificationService.swift
import UserNotifications

class NotificationService: UNNotificationServiceExtension {
    var contentHandler: ((UNNotificationContent) -> Void)?
    var bestAttemptContent: UNMutableNotificationContent?

    override func didReceive(_ request: UNNotificationRequest, withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void) {
        self.contentHandler = contentHandler
        bestAttemptContent = (request.content.mutableCopy() as? UNMutableNotificationContent)
        if let bestAttemptContent = bestAttemptContent {
            // Modify the notification content here...
            bestAttemptContent.title = "\(bestAttemptContent.title) [modified]"
            contentHandler(bestAttemptContent)
        }
    }

    override func serviceExtensionTimeWillExpire() {
        // Called just before the extension will be terminated by the system.
        // Use this as an opportunity to deliver your "best attempt" at modified content, otherwise the original push payload will be used.
        if let contentHandler = contentHandler, let bestAttemptContent =  bestAttemptContent {
            contentHandler(bestAttemptContent)
        }
    }
}

// NotificationService.swift
import UserNotifications

class NotificationService: UNNotificationServiceExtension {
    var contentHandler: ((UNNotificationContent) -> Void)?
    var bestAttemptContent: UNMutableNotificationContent?

    override func didReceive(_ request: UNNotificationRequest, withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void) {
        self.contentHandler = contentHandler
        bestAttemptContent = (request.content.mutableCopy() as? UNMutableNotificationContent)
        if let bestAttemptContent = bestAttemptContent {           
             contentHandler(bestAttemptContent)
        }
        
        // start ringing, VibratorFeature.start() needs to be implemented by yourself
        VibratorFeature.start()
    }

    override func serviceExtensionTimeWillExpire() {
        if let contentHandler = contentHandler, let bestAttemptContent =  bestAttemptContent {
            /// If there is no response for more than 30 seconds, the vibration and ringing function will be turned off.
            // stop ringing, RingingFeature.shared.stop() needs to be implemented by yourself
            VibratorFeature.stop()
            contentHandler(bestAttemptContent)
        }
    }
}

// Versions prior to iOS 13 monitor the foreground or background status through AppDelegate applicationWillEnterForeground
// AppDelegate.swift
class AppDelegate: UIResponder, UIApplicationDelegate {
    func applicationWillEnterForeground(_ application: UIApplication) {
      ...    
      sendStopRingingToExtension()
    }
    func sendStopRingingToExtension() {
        CFNotificationCenterPostNotification(CFNotificationCenterGetDarwinNotifyCenter(),
                                             CFNotificationName("APNsStopRinging" as CFString), nil, nil, true)
    }
}

// Starting from iOS 13, monitor the foreground or background status through SceneDelegate sceneWillEnterForeground
// SceneDelegate.swift
class SceneDelegate: UIResponder, UIWindowSceneDelegate {
    func sceneWillEnterForeground(_ scene: UIScene) {
        ...
        sendStopRingingToExtension()
    }

    func sendStopRingingToExtension() {
        CFNotificationCenterPostNotification(CFNotificationCenterGetDarwinNotifyCenter(),
                                             CFNotificationName("APNsStopRinging" as CFString), nil, nil, true)
    }
}


// NotificationService.swift
import UserNotifications

class NotificationService: UNNotificationServiceExtension {
    var contentHandler: ((UNNotificationContent) -> Void)?
    var bestAttemptContent: UNMutableNotificationContent?

    override func didReceive(_ request: UNNotificationRequest, withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void) {
        self.contentHandler = contentHandler
        bestAttemptContent = (request.content.mutableCopy() as? UNMutableNotificationContent)
        if let bestAttemptContent = bestAttemptContent {        
            contentHandler(bestAttemptContent)
        }
        
        // start ringing, VibratorFeature.start() needs to be implemented by yourself
        VibratorFeature.start()
        registerObserver()
    }

    override func serviceExtensionTimeWillExpire() {
        if let contentHandler = contentHandler, let bestAttemptContent =  bestAttemptContent {
            /// If there is no response for more than 30 seconds, the vibration and ringing function will be turned off.
            // stop ringing, RingingFeature.shared.stop() needs to be implemented by yourself
            VibratorFeature.stop()
            contentHandler(bestAttemptContent)
        }
    }
    
    private func registerObserver() {
        CFNotificationCenterAddObserver(CFNotificationCenterGetDarwinNotifyCenter(),
                                        Unmanaged.passUnretained(self).toOpaque(), { center, pointer, name, _, userInfo in
            VibratorFeature.stop()
        }, "APNsStopRinging" as CFString, nil, .deliverImmediately)
    }
}