AVFoundation.swift

import AVFoundation
import UIKit.UIView

extension AVCaptureVideoPreviewLayer {
    static func createAsSublayer(of superView: UIView, session: AVCaptureSession) {
        let previewLayer = Self.init(session: session)
        previewLayer.videoGravity = AVLayerVideoGravity.resizeAspectFill
        let rootLayer = superView.layer
        previewLayer.frame = rootLayer.bounds
        rootLayer.addSublayer(previewLayer)
    }
}

extension UIDeviceOrientation {
    var imageOrientation: CGImagePropertyOrientation {
        switch self {
        case .portraitUpsideDown: return .left
        case .landscapeLeft: return .upMirrored
        case .landscapeRight: return .down
        default: return .up
        }
    }
}

extension AVCaptureDeviceInput {
    static var defaultDevice: AVCaptureDeviceInput {
        do {
            guard let videoDevice = AVCaptureDevice
                .DiscoverySession(
                    deviceTypes: [.builtInWideAngleCamera],
                    mediaType: .video,
                    position: .back)
                    .devices
                .first else { fatalError("No capture device found") }
            return try AVCaptureDeviceInput(device: videoDevice)
        } catch {
            fatalError(String(describing: error))
        }
    }
}