ios - 如何将 AVCaptureVideoPreviewLayer 旋转 90 度以在 iOS11 中更正它？

Question

我有一个 AVCaptureVideoPreviewLayer，它设置为使用前置摄像头源捕获 session 的实时预览。但是，输出旋转了 90 度，我试图让该层与我的应用程序的其余部分对齐，该应用程序处于 Landscape 方向。有没有办法将它旋转 90 度 以更正它？

到目前为止，这是我的代码:

override func viewDidLoad() {
    super.viewDidLoad()

    let captureSession = AVCaptureSession()

    guard let captureDevice = getDevice(position: .front) else { return }
    guard let input = try? AVCaptureDeviceInput(device: captureDevice) else { return }
    captureSession.addInput(input)

    captureSession.startRunning()

    let previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
    view.layer.addSublayer(previewLayer)
    previewLayer.frame = view.frame
    previewLayer.videoGravity = .resizeAspectFill
    previewLayer.connection?.automaticallyAdjustsVideoMirroring = false
    previewLayer.connection?.isVideoMirrored = false
}

func getDevice(position: AVCaptureDevice.Position) -> AVCaptureDevice? {
    let devices = AVCaptureDevice.devices() as NSArray;
    for de in devices {
        let deviceConverted = de as! AVCaptureDevice
        if(deviceConverted.position == position){
            return deviceConverted
        }
    }
    return nil
}

Answer 1

能否将 previewLayer 添加到另一个 UIView 中，然后像这样旋转:

private var captureView: UIView!

override func viewDidLoad() {
    super.viewDidLoad()

    self.captureView = UIView(frame: self.view.bounds)
    self.captureView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
    self.view.addSubview(captureView)

    // ...
    captureView.layer.addSublayer(previewLayer)
    // ...

    self.rotateView(animated: false)
}

// Rotating captureView based on device orientation
func rotateView(animated: Bool) {
    var transform: CGAffineTransform?
    switch UIDevice.current.orientation {
    case .portraitUpsideDown:
        transform = CGAffineTransform(rotationAngle: CGFloat.pi)
    case .landscapeLeft:
        transform = CGAffineTransform(rotationAngle: CGFloat.pi / 2)
    case .landscapeRight:
        transform = CGAffineTransform(rotationAngle: -CGFloat.pi / 2)
    default:
        break
    }

    guard animated else {
        self.captureView.transform(transform)
        return
    }

    UIView.animate(withDuration: 0.5, animations: {[weak self] in
        self?.captureView.transform(transform)
    })
}