My Code private let synthesizer = AVSpeechSynthesizer() override func didReceive(_ request: UNNotificationRequest, withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void) { self.contentHandler = contentHandler bestAttemptContent = (request.content.mutableCopy() as? UNMutableNotificationContent) do { try AVAudioSession.sharedInstance().setCategory(AVAudioSession.Category.playback) let utterance = AVSpeechUtterance(string: "Hello Sim") utterance.voice = AVSpeechSynthesisVoice(language: "th_TH") utterance.rate = 1.0 utterance.pitchMultiplier = 1.0 utterance.volume = 1.0 utterance.preUtteranceDelay = 0 self.synthesizer.usesApplicationAudioSession = false self.synthesizer.speak(utterance) } catch { print(error.localizedDescription) } if let bestAttemptContent = self.bestAttemptContent { contentHandler(bestAttemptContent) } } Info.plist enable UIBackgroundModes audio fetch processing remote-notification payloadNotification { "aps":{ "alert":{ "title":"title" "subtitle":"subtitle" "body":"body" } "mutable-content":1 "content-available":1 "sound":"tester.caf" } } This code can play in simulator but can't play in real device