录音有时会创建一个长度为0秒的文件

如何解决录音有时会创建一个长度为0秒的文件

我正在制作一个录制音频的应用程序，它以动画方式显示波形。 9/10倍的录音效果很好，但是有时文件没有长度，也没有写入任何内容。我到处都有assertionFailure，似乎没有什么错。我真的不知道发生了什么事，因此感谢您的帮助。

private func startRecording() {
        if let d = self.delegate {
            d.didStartRecording()
        }
        
        self.recordingTs = NSDate().timeIntervalSince1970
        self.silenceTs = 0
        
        do {
            let session = AVAudioSession.sharedInstance()
            try session.setCategory(.record,mode: .default)

            try session.setActive(true)
        } catch let error as NSError {
            assertionFailure(error.debugDescription)
            SVProgressHUD.showError(withStatus: error.localizedDescription)
            print(error.localizedDescription)
            return
        }
        
        guard let format = self.format() else {
            assertionFailure("format error")
            SVProgressHUD.showError(withStatus: "Error with Format")
            return
        }
        
        inputNode.installTap(onBus: 0,bufferSize: 1024,format: format) { (buffer,time) in
            let level: Float = -50
            let length: UInt32 = 1024
            buffer.frameLength = length
            let channels = UnsafeBufferPointer(start: buffer.floatChannelData,count: Int(buffer.format.channelCount))
            var value: Float = 0
            vDSP_meamgv(channels[0],1,&value,vDSP_Length(length))
            var average: Float = ((value == 0) ? -100 : 20.0 * log10f(value))
            if average > 0 {
                average = 0
            } else if average < -100 {
                average = -100
            }
            let silent = average < level
            let ts = NSDate().timeIntervalSince1970
            if ts - self.renderTs > 0.1 {
                let floats = UnsafeBufferPointer(start: channels[0],count: Int(buffer.frameLength))
                let frame = floats.map({ (f) -> Int in
                    return Int(f * Float(Int16.max))
                })
                DispatchQueue.main.async {
                    let seconds = (ts - self.recordingTs)
                    self.timeLabel.text = seconds.toTimeString
                    self.renderTs = ts
                    let len = self.audioView.waveforms.count
                    for i in 0 ..< len {
                        let idx = ((frame.count - 1) * i) / len
                        let f: Float = sqrt(1.5 * abs(Float(frame[idx])) / Float(Int16.max))
                        self.audioView.waveforms[i] = min(49,Int(f * 50))
                    }
                    self.audioView.active = !silent
                    self.audioView.setNeedsDisplay()
                }
            }
            
            let write = true
            if write {
                if self.audioFile == nil {
                    self.audioFile = self.createAudioRecordFile()
                }
                if let f = self.audioFile {
                    do {
                        print("buffer.frameLength \(buffer.debugDescription)")
                        try f.write(from: buffer)
                    } catch let error as NSError {
                        SVProgressHUD.showError(withStatus: "Error. \(error.localizedDescription)")
                        assertionFailure("Error. \(error.localizedDescription)")
                        print(error.localizedDescription)
                    }
                }
            }
        }
        do {
            self.audioEngine.prepare()
            try self.audioEngine.start()
        } catch let error as NSError {
            SVProgressHUD.showError(withStatus: "Error. \(error.localizedDescription)")
            assertionFailure("Error. \(error.localizedDescription)")
            print(error.localizedDescription)
            return
        }
    }
    
    private func stopRecording() {
        if let d = self.delegate {
            d.didFinishRecording()
        }

        self.audioFile = nil
        self.audioEngine.inputNode.removeTap(onBus: 0)
        self.audioEngine.stop()
        do {
            try AVAudioSession.sharedInstance().setActive(false)
        } catch  let error as NSError {
            print(error.localizedDescription)
            SVProgressHUD.showError(withStatus: "Error. \(error.localizedDescription)")
            assertionFailure("Error. \(error.localizedDescription)")
            return
        }
        let length1 = length(url: self.createAudioRecordPath()!)
        print("length when stop: \(length1)")
        DispatchQueue.main.asyncAfter(deadline: DispatchTime.now()) {
            let length2 = self.length(url: self.createAudioRecordPath()!)
            print("length when stopedp: \(length2)")
            if length2 < 1 {
                assertionFailure("not length enough")
            }
            self.dismiss(animated: true,completion: nil)
        }
    }