AVCapturePhoto 为什么我的照片总是零？

Question

我正在尝试实现一些类似于 snapchat 的自定义相机。我不明白为什么我的图像在 segue 期间总是 nil。也许一双新的眼睛可能会有所帮助，因为我已经为此工作了 2 天了......

当我点击拍照按钮（至运行 "livePhotoTapped"）时，应用程序崩溃并出现错误：致命错误：在展开可选值时意外发现 nil，指的是图像为 nil

任何帮助都会很好 :)

@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

这样使用：

对于 CMSampleBufferIsValid 检查此 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")
            }
        }
    })
}

Answer 2

您正在强制展开一个 nil 对象。

var currentDevice: AVCaptureDevice?

看起来这个方法已经被弃用了：

+ (NSArray<AVCaptureDevice *> *)devices NS_DEPRECATED(10_7, NA, 4_0, 10_0, "Use AVCaptureDeviceDiscoverySession instead.");

你试过了吗"AVCaptureDeviceDiscoverySession"？

AVCapturePhoto 为什么我的照片总是零？

AVCapturePhoto Why is my photo always nil?

avcapturesession

avcapturedevice

swift

swift3

swift4