Changes active camera between front and rear.

ChangeCamera.swift

    //  MARK: Device Configuration
    
    /// - Tag: ChangeCamera
    public func changeCamera() {
        //        MARK: Here disable all camera operation related buttons due to configuration is due upon and must not be interrupted
        DispatchQueue.main.async {
            self.isCameraButtonDisabled = true
        }
        //
        
        sessionQueue.async {
            let currentVideoDevice = self.videoDeviceInput.device
            let currentPosition = currentVideoDevice.position
            
            let preferredPosition: AVCaptureDevice.Position
            let preferredDeviceType: AVCaptureDevice.DeviceType
            
            switch currentPosition {
            case .unspecified, .front:
                preferredPosition = .back
                preferredDeviceType = .builtInWideAngleCamera
                
            case .back:
                preferredPosition = .front
                preferredDeviceType = .builtInWideAngleCamera
                
            @unknown default:
                print("Unknown capture position. Defaulting to back, dual-camera.")
                preferredPosition = .back
                preferredDeviceType = .builtInWideAngleCamera
            }
            let devices = self.videoDeviceDiscoverySession.devices
            var newVideoDevice: AVCaptureDevice? = nil
            
            // First, seek a device with both the preferred position and device type. Otherwise, seek a device with only the preferred position.
            if let device = devices.first(where: { $0.position == preferredPosition && $0.deviceType == preferredDeviceType }) {
                newVideoDevice = device
            } else if let device = devices.first(where: { $0.position == preferredPosition }) {
                newVideoDevice = device
            }
            
            if let videoDevice = newVideoDevice {
                do {
                    let videoDeviceInput = try AVCaptureDeviceInput(device: videoDevice)
                    
                    self.session.beginConfiguration()
                    
                    // Remove the existing device input first, because AVCaptureSession doesn't support
                    // simultaneous use of the rear and front cameras.
                    self.session.removeInput(self.videoDeviceInput)
                    
                    if self.session.canAddInput(videoDeviceInput) {
                        self.session.addInput(videoDeviceInput)
                        self.videoDeviceInput = videoDeviceInput
                    } else {
                        self.session.addInput(self.videoDeviceInput)
                    }
                    
                    if let connection = self.photoOutput.connection(with: .video) {
                        if connection.isVideoStabilizationSupported {
                            connection.preferredVideoStabilizationMode = .auto
                        }
                    }
                    
                    self.photoOutput.maxPhotoQualityPrioritization = .quality
                    
                    self.session.commitConfiguration()
                } catch {
                    print("Error occurred while creating video device input: \(error)")
                }
            }
            
            DispatchQueue.main.async {
//                MARK: Here enable capture button due to successfull setup
                self.isCameraButtonDisabled = false
            }
        }
    }