Question

根据我之前的问题，我对我的代码进行了很多更改，这些更改已经购买了一组新的问题，这就是为什么我决定创建一个新问题而不是遵循之前的问题。

我正在玩Swift开发，我正在尝试创建一个基本应用程序，在UIImageview内显示相机。

我正在使用AVFoundation框架。

到目前为止，我已经能够在负载下设置前置摄像头了。我的问题是，如何实现按钮点击时切换相机的功能？

我首先初始化实例：

var captureSession = AVCaptureSession()
var sessionOutput = AVCapturePhotoOutput()
var sessionOutputSetting = AVCapturePhotoSettings(format: [AVVideoCodecKey:AVVideoCodecJPEG])
var previewLayer = AVCaptureVideoPreviewLayer()

我还创建了一个切换bool：

// Bool to manage camera toggle. False = front-face (default)
var toggle = false

在viewWillApear我调用pickCamera函数，该函数检查切换值并创建设备恢复会话：

func pickCamera(which: Bool) {
    if (which == true) {
        let deviceDescovery = AVCaptureDeviceDiscoverySession(deviceTypes: [AVCaptureDeviceType.builtInDualCamera, AVCaptureDeviceType.builtInTelephotoCamera, AVCaptureDeviceType.builtInWideAngleCamera], mediaType: AVMediaTypeVideo, position: AVCaptureDevicePosition.back)

        startCamera(deviceDesc: deviceDescovery!)
        toggle = true;

    } else if (which == false) {
        let deviceDescovery = AVCaptureDeviceDiscoverySession(deviceTypes: [AVCaptureDeviceType.builtInDualCamera, AVCaptureDeviceType.builtInTelephotoCamera, AVCaptureDeviceType.builtInWideAngleCamera], mediaType: AVMediaTypeVideo, position: AVCaptureDevicePosition.front)

        startCamera(deviceDesc: deviceDescovery!)
        toggle = false;

    }
}

startCamera函数然后创建并设置captureSession并添加到父图层以显示：

func startCamera(deviceDesc: AVCaptureDeviceDiscoverySession) {
    for device in (deviceDesc.devices)! {
        if (device.position == AVCaptureDevicePosition.back) {
            do {
                let input = try AVCaptureDeviceInput(device: device)
                if (captureSession.canAddInput(input)) {
                    captureSession.addInput(input)

                    if (captureSession.canAddOutput(sessionOutput)) {
                        captureSession.addOutput(sessionOutput)
                        previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
                        previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
                        previewLayer.connection.videoOrientation = AVCaptureVideoOrientation.portrait
                        captureSession.startRunning()
                        cameraView.layer.addSublayer(previewLayer)
                    }
                }
            }
            catch {
                print("Exception")
            }
        } else if (device.position == AVCaptureDevicePosition.front) {
            do {
                let input = try AVCaptureDeviceInput(device: device)
                if (captureSession.canAddInput(input)) {
                    captureSession.addInput(input)

                    if (captureSession.canAddOutput(sessionOutput)) {
                        captureSession.addOutput(sessionOutput)
                        previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
                        previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
                        previewLayer.connection.videoOrientation = AVCaptureVideoOrientation.portrait
                        captureSession.startRunning()
                        cameraView.layer.addSublayer(previewLayer)
                    }
                }
            }
            catch {
                print("Exception")
            }
        }
    }

}

我还添加了一个带动作的按钮：

@IBAction func toggleCamera(_ sender: Any) {
    if (toggle == false) {
        print("Changing to back camera")
        previewLayer.removeFromSuperlayer()
        toggle = true;
        pickCamera(which: true)

    } else if (toggle == true) {
        print("Changing to front camera")
        previewLayer.removeFromSuperlayer()
        toggle = false;
        pickCamera(which: false)
    }
}

toggle方法应该清除当前视图并调用pickCamera方法，该方法应创建备用相机的新实例。

虽然由于某种原因，这不起作用。我猜这与未正确清除前一个视图/正确添加新视图有关，但我又不确定。

感谢您抽出宝贵时间查看我的问题，请询问我是否遗漏了信息或者没有正确解释自己。

更新终于修好了。问题在于在创建新captureSession之前未停止当前captureSession。

要解决此问题，我更新了toggleCamera功能以包含：

let currentCameraInput: AVCaptureInput = captureSession.inputs[0] as! AVCaptureInput

对于对代码感兴趣的任何人，请查看here

切换前/后相机

0 个答案: