如何实现从前置摄像头到后置摄像头的切换

问题描述

下面是相机部分的代码，我尝试添加一个布尔值来检测何时激活前置摄像头，但收到错误消息。

Below is the code for the camera section, I tried adding in a boolean to detect when the front camera is activated but I receive an error.

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()
    }
}

推荐答案

您的问题是您没有检查是否可以在将输入和/或输出添加到捕获文件之前添加它们离子。顺便说一句，您在切换相机时不需要再次设置预览层，并且只需要一个captureDevice：

Your problem is that you are not checking if you can add input and/or output before adding them to your capture session. Btw you don't need to setup the preview layer again when switching your camera and you need only one 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：

Your CollectionViewCell code should look something like this:

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()
    }
}

这篇关于如何实现从前置摄像头到后置摄像头的切换的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！