Question

下面是相机部分的代码，我尝试添加一个布尔值来检测前置摄像头何时被激活但是我收到错误。

import UIKit
import AVFoundation 
class MainCameraCollectionViewCell: UICollectionViewCell {
    @IBOutlet weak var myView: UIView!
    var captureSession = AVCaptureSession()
    var backCamera: AVCaptureDevice?
    var frontCamera: AVCaptureDevice?
    var currentCamera: AVCaptureDevice?
    var photoOutPut: AVCapturePhotoOutput?
    var cameraPreviewLayer: AVCaptureVideoPreviewLayer?
    var image: UIImage?
    var usingFrontCamera = false   
    override func awakeFromNib() {
        super.awakeFromNib()
        setupCaptureSession()
        setupDevice()
        setupInput()
        setupPreviewLayer()
        startRunningCaptureSession()
    }
    func setupCaptureSession(){
        captureSession.sessionPreset = AVCaptureSession.Preset.photo
    }
    func setupDevice(usingFrontCamera:Bool = false){
        let deviceDiscoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [AVCaptureDevice.DeviceType.builtInWideAngleCamera], mediaType: AVMediaType.video, position: AVCaptureDevice.Position.unspecified)
        let devices = deviceDiscoverySession.devices   
        for device in devices {
            if device.position == AVCaptureDevice.Position.back {
                backCamera = device
            } else if device.position == AVCaptureDevice.Position.front {
                frontCamera = device
            }
        }
        if usingFrontCamera {
            currentCamera = frontCamera
        } else {
            currentCamera = backCamera
        }
    }
    func setupInput() {
        do {
            let captureDeviceInput = try AVCaptureDeviceInput(device: currentCamera!)
            captureSession.addInput(captureDeviceInput)
            photoOutPut = AVCapturePhotoOutput()
            photoOutPut?.setPreparedPhotoSettingsArray([AVCapturePhotoSettings(format:[AVVideoCodecKey: AVVideoCodecType.jpeg])], completionHandler: nil)
            captureSession.addOutput(photoOutPut!)
        } catch {
            print(error)
        }
    }
    func setupPreviewLayer(){
        cameraPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
        cameraPreviewLayer?.videoGravity = AVLayerVideoGravity.resizeAspectFill
        cameraPreviewLayer?.connection?.videoOrientation = AVCaptureVideoOrientation.portrait
        cameraPreviewLayer?.frame = CGRect(x: 0, y: 0, width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height)
        self.layer.insertSublayer(cameraPreviewLayer!, at: 0)
    }
    func startRunningCaptureSession(){
        captureSession.startRunning()
    }
    @IBAction func cameraButton_TouchUpInside(_ sender: Any) {
        let settings = AVCapturePhotoSettings()
        photoOutPut?.capturePhoto(with: settings, delegate: self as! AVCapturePhotoCaptureDelegate)
    }
    //Flip to front and back camera
    @IBAction func FlipThe_camera(_ sender: UIButton) {
        print("Flip touched")
        if let inputs = captureSession.inputs as? [AVCaptureDeviceInput] {
            for input in inputs {
                captureSession.removeInput(input)
            }
        }
        usingFrontCamera = !usingFrontCamera
        setupCaptureSession()
        setupDevice(usingFrontCamera:usingFrontCamera)
        setupInput()
        setupPreviewLayer()
        startRunningCaptureSession()
    }
}

collectionViewAttemptOfPagingAttempt002 [2908：834004] *终止应用程序由于未捕获的异常'NSInvalidArgumentException'，原因： '* - [AVCaptureSession addOutput：]无法添加输出捕获会话 - ＆GT; - ＆GT;因为同一类型的多个输出是不支持的'

Answer 1

您的问题是，在将其添加到捕获会话之前，您不会检查是否可以添加输入和/或输出。如果您在切换相机时不需要再次设置预览图层，则只需要一个captureDevice：

if captureSession.canAddInput(captureDeviceInput) {
    captureSession.addInput(captureDeviceInput)
}

和

if captureSession.canAddOutput(photoOutPut) {
    captureSession.addOutput(photoOutPut)
}

您的CollectionViewCell代码应如下所示：

class MainCameraCollectionViewCell: UICollectionViewCell, AVCapturePhotoCaptureDelegate {
    private var captureSession = AVCaptureSession()
    private var sessionQueue: DispatchQueue!
    private var captureDevice: AVCaptureDevice!
    private  var photoOutPut: AVCapturePhotoOutput!
    private var cameraPreviewLayer: AVCaptureVideoPreviewLayer!
    var image: UIImage?
    var usingFrontCamera = false
    override func awakeFromNib() {
        super.awakeFromNib()
        setupCaptureSession()
        setupDevice()
        setupInput()
        setupPreviewLayer()
        startRunningCaptureSession()
    }
    func setupCaptureSession(){
        captureSession.sessionPreset = .photo
        sessionQueue = DispatchQueue(label: "session queue")
    }
    func setupDevice(usingFrontCamera: Bool = false){
        sessionQueue.async {
            let deviceDiscoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInWideAngleCamera], mediaType: .video, position: .unspecified)
            let devices = deviceDiscoverySession.devices
            for device in devices {
                if usingFrontCamera && device.position == .front {
                    self.captureDevice = device
                } else if device.position == .back {
                    self.captureDevice = device
                }
            }
        }
    }
    func setupInput() {
        sessionQueue.async {
            do {
                let captureDeviceInput = try AVCaptureDeviceInput(device: self.captureDevice)
                if self.captureSession.canAddInput(captureDeviceInput) {
                    self.captureSession.addInput(captureDeviceInput)
                }
                self.photoOutPut = AVCapturePhotoOutput()
                self.photoOutPut.setPreparedPhotoSettingsArray([AVCapturePhotoSettings(format:[AVVideoCodecKey: AVVideoCodecType.jpeg])], completionHandler: nil)
                if self.captureSession.canAddOutput(self.photoOutPut) {
                    self.captureSession.addOutput(self.photoOutPut)
                }
            } catch {
                print(error)
            }
        }
    }
    func setupPreviewLayer() {
        cameraPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
        cameraPreviewLayer.videoGravity = .resizeAspectFill
        cameraPreviewLayer.connection?.videoOrientation = .portrait
        cameraPreviewLayer.frame = UIScreen.main.bounds
        layer.insertSublayer(cameraPreviewLayer, at: 0)
    }
    func startRunningCaptureSession() {
        captureSession.startRunning()
    }
    @IBAction func cameraButton_TouchUpInside(_ sender: Any) {
        let settings = AVCapturePhotoSettings()
        photoOutPut.capturePhoto(with: settings, delegate: self)
    }
    //Flip to front and back camera
    @IBAction func FlipThe_camera(_ sender: UIButton) {
        captureSession.beginConfiguration()
        if let inputs = captureSession.inputs as? [AVCaptureDeviceInput] {
            for input in inputs {
                captureSession.removeInput(input)
            }
        }
        usingFrontCamera = !usingFrontCamera
        setupCaptureSession()
        setupDevice(usingFrontCamera: usingFrontCamera)
        setupInput()
        captureSession.commitConfiguration()
        startRunningCaptureSession()
    }
}

Sample project

如何实现从前后摄像头更换摄像头

1 个答案: