swift - 正在刷新 AVCaptureSession...？

Question

弹出 View Controller 时，我在使用 AVCaptureSession 时遇到一些困难。我在导航 Controller 中有一个 View Controller ，用户可以在其中拍照。捕获照片后，我转到“预览照片” View Controller 。如果用户不喜欢这张照片，他们可以返回重新拍摄。当我弹出预览照片 View Controller 时，应用程序崩溃并显示错误“当前不支持多个音频/视频 AVCaptureInputs”

我想也许我可以删除/刷新输入 session ，但它仍然崩溃。

非常感谢任何支持/建议!

继续:

 @IBAction func cancelPressed(_ sender: UIButton) {
    _ = self.navigationController?.popViewController(animated: true)
}

相机配置(工作正常):

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 {

        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 
}

我尝试过的(如果发送者是预览照片 Controller ，则会出现删除 View 中的输入):

func refreshCamera() {

    captureSession.beginConfiguration()

    for input in captureSession.inputs {

        captureSession.removeInput(input as! AVCaptureDeviceInput)

    }
        captureSession.commitConfiguration()

}

Answer 1

这比我想象的要简单得多。只需要在调用 setupCameraSession 方法之前先检查是否已经有输入:

if captureSession.inputs.isEmpty {

setupCaptureSessionCamera()

}