如何将导航栏带到相机框架的顶部

Question

我在应用程序中创建QR代码扫描仪。它包括导航栏，QRCode摄像头和结果框。这是我想做的。带有导航栏

但是当我在手机上运行时，导航栏在相机框架后面。没有导航栏

我试图将导航栏的插座插入我的代码中，然后插入添加view.bringSubview(toFront: navigationbar)，但Xcode表示这不是UIview，所以我遇到了错误。我是iOS开发的新手，任何帮助将不胜感激。

这是我的代码的一部分：

    var captureSession:AVCaptureSession?
    var videoPreviewLayer:AVCaptureVideoPreviewLayer?
    var qrCodeFrameView:UIView?
     @IBOutlet weak var messageLabel: UILabel!
    // Added to support different barcodes
    let supportedBarCodes = [AVMetadataObjectTypeQRCode, AVMetadataObjectTypeCode128Code, AVMetadataObjectTypeCode39Code, AVMetadataObjectTypeCode93Code, AVMetadataObjectTypeUPCECode, AVMetadataObjectTypePDF417Code, AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypeAztecCode]
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        let captureDevice = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)
        do {
            // Get an instance of the AVCaptureDeviceInput class using the previous device object.
            let input = try AVCaptureDeviceInput(device: captureDevice)
            // Initialize the captureSession object.
            captureSession = AVCaptureSession()
            // Set the input device on the capture session.
            captureSession?.addInput(input)
            // Initialize a AVCaptureMetadataOutput object and set it as the output device to the capture session.
            let captureMetadataOutput = AVCaptureMetadataOutput()
            captureSession?.addOutput(captureMetadataOutput)
            // Set delegate and use the default dispatch queue to execute the call back
            captureMetadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
            // Detect all the supported bar code
            captureMetadataOutput.metadataObjectTypes = supportedBarCodes
            // Initialize the video preview layer and add it as a sublayer to the viewPreview view's layer.
            videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
            videoPreviewLayer?.videoGravity = AVLayerVideoGravityResizeAspectFill
            videoPreviewLayer?.frame = view.layer.bounds
            view.layer.addSublayer(videoPreviewLayer!)
            // Start video capture
            captureSession?.startRunning()
            // Move the message label to the top view
            view.bringSubview(toFront: messageLabel)
            // Initialize QR Code Frame to highlight the QR code
            qrCodeFrameView = UIView()
            if let qrCodeFrameView = qrCodeFrameView {
                qrCodeFrameView.layer.borderColor = UIColor.green.cgColor
                qrCodeFrameView.layer.borderWidth = 2
                view.addSubview(qrCodeFrameView)
                view.bringSubview(toFront: qrCodeFrameView)
            }
        } catch {
            // If any error occurs, simply print it out and don't continue any more.
            print(error)
            return
        }

Answer 1

尝试替换以下内容：

view.layer.addSublayer(videoPreviewLayer!)

with：

view.layer.insertSublayer(videoPreviewLayer!, below: qrCodeFrameView.layer) //Or below: messageLabel.layer

尽量不要将子层添加到顶部，而只需将其插入已经存在的其他一些子视图下方，它将确保NAV栏正确显示