ios - 在前后摄像头之间切换

Question

我正在尝试制作一个自定义的 cameraView，到目前为止它可以正常工作。但是我遇到了在前后摄像头之间切换的问题。我试图通过自定义枚举来处理它。但是当 switchCamera 方法被调用时。它似乎只是卡住了相机？怎么会这样？

相机变量

var camera = CameraType.Back

viewDidLoad

    switchButton = UIButton(frame: CGRectMake(rightButtonXPoint, 35, 30, 30))
    switchButton.setImage(UIImage(named: "Switch"), forState: UIControlState.Normal)
    switchButton.addTarget(self, action: "switchCamera", forControlEvents: UIControlEvents.TouchUpInside)
    actionView.addSubview(switchButton)

ViewWillAppear

override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated)

    reloadCamera()


}

切换相机

func switchCamera() {

    if camera == CameraType.Back {
        camera = CameraType.Front
    } else {
        camera = CameraType.Back
    }
    reloadCamera()
}

重新加载相机

func reloadCamera() {

    captureSession = AVCaptureSession()


   // let backCamera = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)
    var captureDevice:AVCaptureDevice! = nil
    if (camera == CameraType.Front) {
        let videoDevices = AVCaptureDevice.devicesWithMediaType(AVMediaTypeVideo)

        for device in videoDevices{
            let device = device as! AVCaptureDevice
            if device.position == AVCaptureDevicePosition.Front {
                captureDevice = device
                break
            }
        }
    } else {
        captureDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)
    }

    do {
        let input = try? AVCaptureDeviceInput(device: captureDevice)

        if (captureSession?.canAddInput(input) != nil){

            captureSession?.addInput(input)

            stillImageOutput = AVCaptureStillImageOutput()
            stillImageOutput?.outputSettings = [AVVideoCodecKey : AVVideoCodecJPEG]

            if (captureSession?.canAddOutput(stillImageOutput) != nil){
                captureSession?.addOutput(stillImageOutput)

                previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)

                previewLayer?.videoGravity = AVLayerVideoGravityResizeAspect
                previewLayer?.connection.videoOrientation = AVCaptureVideoOrientation.Portrait
                cameraView.layer.addSublayer(previewLayer!)
                captureSession?.startRunning()

            }

            cameraView.bringSubviewToFront(actionView)
            previewImageView.bringSubviewToFront(actionView)
            self.previewImageView.hidden = true


        }
    }







}

Answer 1

在不知 Prop 体细节的情况下，很难猜测，但看看你的代码，我认为你遇到的问题是你试图向 session 添加多个摄像头(每次切换时，您实际上是在尝试添加新设备)。

测试捕获 session 是否正在运行，如果是，则在添加新设备之前移除现有设备(后置/前置摄像头)。确保将其包装为这样的交易:

func beginSession(captureDevice : AVCaptureDevice?) {        

    if captureSession.running {
        captureSession.beginConfiguration()

        let currentInput : AVCaptureInput = captureSession.inputs[0] as! AVCaptureInput
        captureSession.removeInput(currentInput)

        do {
            try captureSession.addInput(AVCaptureDeviceInput(device: captureDevice))
        } catch {
            print("Error adding video input device")
        }

        captureSession.commitConfiguration()

    } else {
        // Setup the camera and layer for the first time.
        do {
            try captureSession.addInput(AVCaptureDeviceInput(device: captureDevice))
        } catch {
            print("Error adding video input device")
        }


        previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
        self.view.layer.insertSublayer(previewLayer!, atIndex: 0)
        previewLayer?.frame = self.view.layer.frame
        captureSession.startRunning()
    }
}

这是一个相当简单但实用的示例。我只是每次都传递捕获设备(根据需要使用前置/后置摄像头)，它在我的代码中运行良好。非常原型(prototype)实现，但希望这能为您提供缺少的步骤:

1. .beginConfiguration() 在更改正在运行的 session 之前。
2. 删除现有设备，然后添加新设备。
3. .commitConfiguration() 使一切正常。

无需删除预览层，因为它已经连接到您的 currentSession。