swift - 改进 Swift 中的条码扫描器

Question

我已经按照教程中的“标准”实现了条形码扫描。但我认为表演有点糟糕。我可以将我的相机对准条码，对焦完美且无眩光，但代码仍然检测不到条码。

我有点嫉妒 ScanLife 应用程序 - 它速度惊人，甚至无需聚焦即可检测代码。

有什么改进扫描的想法吗？

这是我的代码片段(检测部分):

var captureSession: AVCaptureSession!
    var previewLayer: AVCaptureVideoPreviewLayer!
    let videoCaptureDevice = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)

    captureSession = AVCaptureSession()

    let videoInput: AVCaptureDeviceInput

    do {
        videoInput = try AVCaptureDeviceInput(device: videoCaptureDevice)

        if captureSession.canAddInput(videoInput) {
            captureSession.addInput(videoInput)

            let metadataOutput = AVCaptureMetadataOutput()

            if captureSession.canAddOutput(metadataOutput) {
                captureSession.addOutput(metadataOutput)

                metadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
                metadataOutput.metadataObjectTypes = metadataOutput.availableMetadataObjectTypes // Use all metadata object types by default.
                metadataOutput.rectOfInterest = CGRect.zero

            } else {
                failed()
                return
            }

            if (videoCaptureDevice?.isFocusModeSupported(.continuousAutoFocus))! {
                do {
                    if(try videoCaptureDevice?.lockForConfiguration()) != nil {
                        videoCaptureDevice?.exposureMode = .continuousAutoExposure
                        videoCaptureDevice?.focusMode = .continuousAutoFocus
                        videoCaptureDevice?.unlockForConfiguration()
                    }
                } catch {

                }
            }

            videoCaptureDevice?.addObserver(self, forKeyPath: "adjustingFocus", options: NSKeyValueObservingOptions.new, context: nil)
            let tapGesture = UITapGestureRecognizer(target: self, action: #selector(ScannerViewController.focus(_:)))
            mainView.addGestureRecognizer(tapGesture)

            previewLayer = AVCaptureVideoPreviewLayer(session: captureSession);
            previewLayer.frame = view.layer.bounds;
            previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
            mainView.layer.addSublayer(previewLayer);

            /*
            // Initialize code Frame to highlight the code
            codeFrameView.layer.borderColor = UIColor.green.cgColor
            codeFrameView.layer.borderWidth = 2
            view.addSubview(codeFrameView)
            view.bringSubview(toFront: codeFrameView)
            */

            captureSession.startRunning()

        } else {
            failed()
        }
    } catch {
        failed()
    }

Answer 1

就其值(value)而言，定义要搜索的矩形似乎可以提高性能。另外如文档所述:

Specifying a rectOfInterest may improve detection performance for certain types of metadata.

代码可以是

metadataOutput.rectOfInterest = focusView.frame

其中focusView是显示在预览层之上的view，用来发信号