Stop speech recognition when user is finished speaking

问题

How is Siri is able to determine when I'm finished speaking. The reason I would like to know is that I would like to implement similar functionality with Apple's Speech Recognition API with my app. Is this doable, or is the only way to know when the user has stopped speaking is via user input?

回答1:

You can use a timer, i had the same problem and I could not solve it with an elegant method.

fileprivate var timer:Timer?
func startRecordingTimer() {
    lastString = ""
    createTimerTimer(4)
}
func stopRecordingTimer() {
    timer?.invalidate()
    timer = nil
}
fileprivate func whileRecordingTimer() {
    createTimerTimer(2)
}
fileprivate var lastString = ""
func createTimerTimer(_ interval:Double) {
    OperationQueue.main.addOperation({[unowned self] in
        self.timer?.invalidate()
        self.timer = Timer.scheduledTimer(withTimeInterval: interval, repeats: false) { (_) in
            self.timer?.invalidate()
            if(self.lastString.characters.count > 0){
                //DO SOMETHING
            }else{
                self.whileRecordingTimer()
            }
        }
    })
}

and in SFSpeechRecognitionTaskDelegate

public func speechRecognitionTask(_ task: SFSpeechRecognitionTask, didHypothesizeTranscription transcription: SFTranscription) {
    let result = transcription.formattedString
    lastString = result
}

来源：https://stackoverflow.com/questions/41421159/stop-speech-recognition-when-user-is-finished-speaking