迅速的照片捕捉黑色圖像

Question

我正在嘗試使用Swift設置AVFoundation照片捕獲。 預覽窗口可以正常工作，但是當我按下按鈕捕獲照片時，啟動該應用程序后拍攝的第一張照片完全是黑色的。 我在運行該應用程序的同一實例中拍攝的所有后續照片均能正常工作，但第一個照片始終只是一個黑色矩形。 拍攝照片時，預覽層也會閃爍黑色。 這是我用於相機的代碼：

import UIKit
import AVFoundation

class photoCaptureViewController: UIViewController {

let session                     : AVCaptureSession = AVCaptureSession()
var previewLayer                : AVCaptureVideoPreviewLayer!
var output = AVCaptureStillImageOutput()
var capturedImage               : UIImage!

override func viewDidLoad() {
    super.viewDidLoad()

  let device = getFrontCamera()
  var error   : NSError? = nil

  let input   : AVCaptureDeviceInput? = AVCaptureDeviceInput.deviceInputWithDevice(device, error: &error) as? AVCaptureDeviceInput

  if input != nil {
    session.addInput(input)
  }else{
    println(error)
  }

  session.sessionPreset = AVCaptureSessionPresetPhoto

  previewLayer = AVCaptureVideoPreviewLayer.layerWithSession(session) as! AVCaptureVideoPreviewLayer
  previewLayer.frame = CGRectMake(0, 0, 300, 300)
  previewLayer.setAffineTransform( CGAffineTransformTranslate(CGAffineTransformMakeScale(0.33, 0.33), -375, -480) )
  previewLayer.position = CGPointMake((photoButton.layer.position.x + 70), (photoButton.layer.position.y - 45))

  previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;

  self.view.layer.addSublayer(previewLayer)

  self.setPreviewOrientation()

  session.startRunning()

}

func setPreviewOrientation() {
  let previewLayerConnection: AVCaptureConnection = self.previewLayer.connection
  let orientation = AVCaptureVideoOrientation(rawValue: UIDevice.currentDevice().orientation.rawValue)
  previewLayerConnection.videoOrientation = orientation!
}

@IBAction func photoButtonPressed(sender: UIButton)
{

  output.outputSettings = [AVVideoCodecKey: AVVideoCodecJPEG]

  if session.canAddOutput(output)
  {
    session.addOutput(output)
  }

  var videoConnection = output.connectionWithMediaType(AVMediaTypeVideo)

  if videoConnection != nil {
    output.captureStillImageAsynchronouslyFromConnection(output.connectionWithMediaType(AVMediaTypeVideo))
      { (imageDataSampleBuffer, error) -> Void in
        self.capturedImage = UIImage(data: AVCaptureStillImageOutput.jpegStillImageNSDataRepresentation(imageDataSampleBuffer))

        UIImageWriteToSavedPhotosAlbum(self.capturedImage, self,nil, nil)

    }}


}

func getFrontCamera() -> AVCaptureDevice{
  var result : AVCaptureDevice!
  var devices = AVCaptureDevice.devicesWithMediaType(AVMediaTypeVideo)
  for device in devices{
    if (device.position == AVCaptureDevicePosition.Front) {
      result = device as! AVCaptureDevice
    }
  }
  return result
}

}

Answer 1

這是通過移動

 output.outputSettings = [AVVideoCodecKey: AVVideoCodecJPEG]

if session.canAddOutput(output)
{
  session.addOutput(output)
}

而不是將其包含在照片捕獲功能中。