从前置摄像头拍摄4次照片后，应用程序崩溃了

Question

当我将相机从后向前翻转并点按四次拍照时，应用程序崩溃时出现以下错误：

  

[AVCapturePhotoOutput capturePhotoWithSettings：delegate：]没有有效和启用的视频连接'

以下是我认为与问题密切相关的两段代码

特别是失败点可以缩小到

photoOutPut?.capturePhoto(with: settings, delegate: self as AVCapturePhotoCaptureDelegate)

相机按钮

@IBAction func cameraButton_TouchUpInside(_ sender: Any) {
    let settings = AVCapturePhotoSettings()
    photoOutPut?.capturePhoto(with: settings, delegate: self as AVCapturePhotoCaptureDelegate)
    print("camera button touched")
}

翻转按钮

@IBAction func FlipThe_camera(_ sender: UIButton) {
print("Flip Touched")
    captureSession.beginConfiguration()
    if let inputs = captureSession.inputs as? [AVCaptureDeviceInput] {
        for input in inputs {
            captureSession.removeInput(input)
        }
    }
    usingFrontCamera = !usingFrontCamera
    setupCaptureSession()
    setupDevice(usingFrontCamera: usingFrontCamera)
    setupInput()
    captureSession.commitConfiguration()
    startRunningCaptureSession()
}
}

我不确定相机会话被禁用的确切时间或位置，因为否则应用程序会平稳运行，只有在翻转后轻触了相机按钮四次才发生此错误。

感谢您的帮助

以下是完整的代码

 import UIKit
 import AVFoundation


 protocol previewSegueDelegate {
func previewSegueDelegate(image:UIImage,device:AVCaptureDevice)
}

class MainCameraCollectionViewCell: UICollectionViewCell {

var gdelegate: gestureDelegate?
var pdelegate: previewSegueDelegate?


@IBOutlet weak var myView: UIView!

var captureSession = AVCaptureSession()
private var sessionQueue: DispatchQueue!
var captureConnection = AVCaptureConnection()
var currentCamera: AVCaptureDevice?

var photoOutPut: AVCapturePhotoOutput?

var cameraPreviewLayer: AVCaptureVideoPreviewLayer?

var image: UIImage?

 var usingFrontCamera = false

override func awakeFromNib() {
    super.awakeFromNib()
    setupCaptureSession()
    setupDevice()
    setupInput()
    setupPreviewLayer()
    startRunningCaptureSession()
    print("Inside of camera cell")
}

func setupCaptureSession(){
    captureSession.sessionPreset = AVCaptureSession.Preset.photo
    sessionQueue = DispatchQueue(label: "session queue")
}

func setupDevice(usingFrontCamera:Bool = false){
    sessionQueue.async {
    let deviceDiscoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [AVCaptureDevice.DeviceType.builtInWideAngleCamera], mediaType: AVMediaType.video, position: AVCaptureDevice.Position.unspecified)
    let devices = deviceDiscoverySession.devices

    for device in devices{
        if usingFrontCamera && device.position == AVCaptureDevice.Position.front {
            self.currentCamera = device
        } else if device.position == AVCaptureDevice.Position.back {
            self.currentCamera = device
        }
    }
    }
}

func setupInput() {
    sessionQueue.async {
        do {
            let captureDeviceInput = try AVCaptureDeviceInput(device: self.currentCamera!)
            if self.captureSession.canAddInput(captureDeviceInput) {
                self.captureSession.addInput(captureDeviceInput)
            }
            self.photoOutPut = AVCapturePhotoOutput()
            self.photoOutPut?.setPreparedPhotoSettingsArray([AVCapturePhotoSettings(format:[AVVideoCodecKey: AVVideoCodecType.jpeg])], completionHandler: nil)
            if self.captureSession.canAddOutput(self.photoOutPut!) {
                self.captureSession.addOutput(self.photoOutPut!)
            }
        } catch {
            print(error)
        }
    }
}
func setupPreviewLayer(){
    cameraPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
    cameraPreviewLayer?.videoGravity = AVLayerVideoGravity.resizeAspectFill
    cameraPreviewLayer?.connection?.videoOrientation = AVCaptureVideoOrientation.portrait
    cameraPreviewLayer?.frame = CGRect(x: 0, y: 0, width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height)
    self.layer.insertSublayer(cameraPreviewLayer!, at: 0)
}

func startRunningCaptureSession(){
    captureSession.startRunning()
}


@IBAction func cameraButton_TouchUpInside(_ sender: Any) {
    let settings = AVCapturePhotoSettings()
    photoOutPut?.capturePhoto(with: settings, delegate: self as AVCapturePhotoCaptureDelegate)
    print("camera button touched")
}

@IBAction func FlipThe_camera(_ sender: UIButton) {
print("Flip Touched")
    captureSession.beginConfiguration()
    if let inputs = captureSession.inputs as? [AVCaptureDeviceInput] {
        for input in inputs {
            captureSession.removeInput(input)
        }
    }
    usingFrontCamera = !usingFrontCamera
    setupCaptureSession()
    setupDevice(usingFrontCamera: usingFrontCamera)
    setupInput()
    captureSession.commitConfiguration()
    startRunningCaptureSession()
}

}


 extension MainCameraCollectionViewCell: AVCapturePhotoCaptureDelegate{
func photoOutput(_ output: AVCapturePhotoOutput, didFinishProcessingPhoto photo: AVCapturePhoto, error: Error?) {
    if let imageData = photo.fileDataRepresentation(){
        print(imageData)
        image = UIImage(data: imageData)
        if(self.image == nil){
            print("The image is empty")
        }
        pdelegate?.previewSegueDelegate(image: self.image!, device: currentCamera!)
    }
}
 }