How can I detect and apply landscape orientation to AVCaptureVideoPreviewLayer in Swift?

Detect and apply it at viewWillLayoutSubviews or if you're using UIView subclass in layoutSubviews.

Here's how:

override func viewWillLayoutSubviews() {                    let orientation: UIDeviceOrientation = UIDevice.current.orientation    previewLayer.connection?.videoOrientation = {        switch (orientation) {        case .portrait:            return .portrait        case .landscapeRight:            return .landscapeLeft        case .landscapeLeft:            return .landscapeRight        default:            return .portrait        }    }()}

update for Swift 3

  override func viewWillLayoutSubviews() {    let orientation: UIDeviceOrientation = UIDevice.current.orientation    print(orientation)    switch (orientation) {    case .portrait:        videoPreviewLayer?.connection.videoOrientation = .portrait    case .landscapeRight:        videoPreviewLayer?.connection.videoOrientation = .landscapeLeft    case .landscapeLeft:        videoPreviewLayer?.connection.videoOrientation = .landscapeRight    case .portraitUpsideDown:            videoPreviewLayer?.connection.videoOrientation = .portraitUpsideDown    default:        videoPreviewLayer?.connection.videoOrientation = .portraitUpsideDown    }}

For me I need it to change orientation when I rotate iPad left or right, the solution that helped me is:

    override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {    let orientation = UIDevice.current.orientation    switch (orientation) {    case .portrait:        videoPreviewLayer?.connection.videoOrientation = .portrait    case .landscapeLeft:        videoPreviewLayer?.connection.videoOrientation = .landscapeRight    case .landscapeRight:        videoPreviewLayer?.connection.videoOrientation = .landscapeLeft    default:        videoPreviewLayer?.connection.videoOrientation = .portrait    }}