SwiftUI - 在 macOS 应用中扫描二维码答案

【问题标题】：SwiftUI - scanning QR codes in the macOS appSwiftUI - 在 macOS 应用中扫描二维码
【发布时间】：2021-08-24 12:09:27
【问题描述】：

我正在开发一个 Mac 应用程序，该应用程序将从相机读取 QR 码，然后从中读取文本。

不幸的是，CodeScanner 包仅适用于 iOS，并且没有调用方法：

func metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], from connection: AVCaptureConnection)

当然，要使用它，必须包含 AVCaptureMetadataOutputObjectsDelegate - 不幸的是，此协议在 macOS 上不可用。

有没有办法使用 SwiftUI 创建 macOS 二维码扫描器？

我目前有一个内置的 MacBook 摄像头预览，但我想念 QR 码丢失的东西：

final class PlayerContainerView: NSViewRepresentable {
    typealias NSViewType = PlayerView
    
    let captureSession: AVCaptureSession
    
    init(captureSession: AVCaptureSession) {
        self.captureSession = captureSession
    }
    
    func makeNSView(context: Context) -> PlayerView {
        return PlayerView(captureSession: captureSession)
    }
    
    func updateNSView(_ nsView: PlayerView, context: Context) {}
}

class PlayerView: NSView {
    var previewLayer: AVCaptureVideoPreviewLayer?
    
    init(captureSession: AVCaptureSession) {
        previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
        super.init(frame: .zero)
        
        setupLayer()
    }
    
    func setupLayer() {
        previewLayer?.frame = self.frame
        previewLayer?.contentsGravity = .resizeAspectFill
        previewLayer?.videoGravity = .resizeAspectFill
        previewLayer?.connection?.automaticallyAdjustsVideoMirroring = false
        
        if let mirroringSupported = previewLayer?.connection?.isVideoMirroringSupported {
            if mirroringSupported {
                previewLayer?.connection?.automaticallyAdjustsVideoMirroring = false
                previewLayer?.connection?.isVideoMirrored = true
            }
        }

        
        layer = previewLayer
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

我找不到任何可以像 AVCaptureMetadataOutputObjectsDelegate 一样工作并允许我捕获元数据对象的委托协议。

【问题讨论】：

标签： swift macos swiftui avfoundation qr-code

【解决方案1】：

我也很惊讶 macOS AVFoundation 不支持AVCaptureMetadataOutput，但CoreImage 支持二维码，这对我有用：

let qrDetector = CIDetector(ofType: CIDetectorTypeQRCode, context: nil, options: nil)!

func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
    guard let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else { return }
    
    let ciImage = CIImage(cvImageBuffer: imageBuffer)
    let features = qrDetector.features(in: ciImage)

    for feature in features {
        let qrCodeFeature = feature as! CIQRCodeFeature
        print("messageString \(qrCodeFeature.messageString!)")
    }
}

可能有更有效的方法来做到这一点。

【讨论】：