AVCapturePhoto Why is my photo always nil?

Question

I'm trying to implement some custom camera similar to snapchat. I cannot see why my image is always nil during segue. Maybe a fresh pair of eyes may help as I have been working on this for 2 days now...

When I tap the take photo button (to run "livePhotoTapped"), app crashes with error: fatal error: unexpectedly found nil while unwrapping an Optional value, referring to the image being nil

Any help would be nice :)

@IBOutlet weak var cameraView: UIView!

//session to capture data
var captureSession = AVCaptureSession()
//which camera to use
var backFacingCamera: AVCaptureDevice?
var frontFacingCamera: AVCaptureDevice?
var currentDevice: AVCaptureDevice?

var stillImageOutput: AVCaptureStillImageOutput?
var stillImage: UIImage?

//camera preview layer
var cameraPreviewLayer: AVCaptureVideoPreviewLayer?


func setupCaptureSessionCamera() {
    //this makes sure to get full res of camera
    captureSession.sessionPreset = AVCaptureSession.Preset.photo

    var devices = AVCaptureDevice.devices(for: .video)

    //query available devices
    for device in devices {

        if device.position == .front {
            frontFacingCamera = device
        } else if device.position == .back {
            backFacingCamera = device
        }
    }//end iteration

    //set a default device
    currentDevice = backFacingCamera

    //configure session w output for capturing still img
    stillImageOutput = AVCaptureStillImageOutput()
    stillImageOutput?.outputSettings = [AVVideoCodecKey : AVVideoCodecType.jpeg]


    do {
        //capture the data from whichevr camera we r using..imagine as buffer to translate data into real world image
        let captureDeviceInput = try AVCaptureDeviceInput(device: currentDevice!)

        captureSession.addInput(captureDeviceInput)
        captureSession.addOutput(stillImageOutput!)

        //setup camera preview layer
        cameraPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)

        //add the preview to our specified view in the UI
        view.layer.addSublayer(cameraPreviewLayer!)
        cameraPreviewLayer?.videoGravity = AVLayerVideoGravity.resizeAspectFill
        cameraPreviewLayer?.frame = cameraView.frame

        captureSession.startRunning()

    } catch let error {

        print(error)

    }//end do 
}

  @IBAction func livePhotoTapped(_ sender: UIButton) {

    let videoConnection = stillImageOutput?.connection(with: .video)

    //capture still image async
    stillImageOutput?.captureStillImageAsynchronously(from: videoConnection!, completionHandler: { (imageDataBuffer, error) in

        if let imageData = AVCapturePhotoOutput.jpegPhotoDataRepresentation(forJPEGSampleBuffer: imageDataBuffer!, previewPhotoSampleBuffer: imageDataBuffer!) {

            self.stillImage = UIImage(data: imageData)
            self.performSegue(withIdentifier: "toPreviewPhoto", sender: self)
        }

    })
}

Answer 1

Use like this :

For CMSampleBufferIsValid check this link

@IBAction func livePhotoTapped(_ sender: UIButton) {

    let videoConnection = stillImageOutput?.connection(with: .video)

    //capture still image async
    stillImageOutput?.captureStillImageAsynchronously(from: videoConnection!, completionHandler: { (imageDataBuffer, error) in

        if error != nil {
            print("error \(error)")
        } else {
            if let imageBuffer = imageDataBuffer, CMSampleBufferIsValid(imageBuffer) {
                if let imageData = AVCapturePhotoOutput.jpegPhotoDataRepresentation(forJPEGSampleBuffer: imageDataBuffer!, previewPhotoSampleBuffer: imageDataBuffer!) {

                    self.stillImage = UIImage(data: imageData)
                    self.performSegue(withIdentifier: "toPreviewPhoto", sender: self)
                }    
            } else {
                print("imageDataBuffer is nil or not valid")
            }
        }
    })
}