QR码不起作用 - 未调用委托方法

Question

我已经看到了许多线程和教程，但没有解决我的问题。我遵循本教程实现简单的QR代码应用程序，但未检测到代码。在QR相关的大多数问题中，该问题与委托方法有关。我已经验证了我正在使用更新的委托方法，但仍然不起作用。

这是我的代码。任何人都可以突出显示我正在做哪种愚蠢的错误。

import UIKit 
import AVFoundation
class QRScannerController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
    @IBOutlet var messageLabel:UILabel!
    @IBOutlet var topbar: UIView!
    var captureSession:AVCaptureSession?
    var videoPreviewLayer:AVCaptureVideoPreviewLayer?
    var qrCodeFrameView:UIView?
    let supportedCodeTypes = [AVMetadataObjectTypeQRCode,
                              AVMetadataObjectTypeCode39Code,
                              AVMetadataObjectTypeUPCECode,
                              AVMetadataObjectTypeCode39Mod43Code,
                              AVMetadataObjectTypeEAN13Code,
                              AVMetadataObjectTypeEAN8Code,
                              AVMetadataObjectTypeCode93Code,
                              AVMetadataObjectTypeCode128Code,
                              AVMetadataObjectTypePDF417Code,
                              AVMetadataObjectTypeAztecCode,
                              AVMetadataObjectTypeInterleaved2of5Code,
                              AVMetadataObjectTypeITF14Code,
                              AVMetadataObjectTypeDataMatrixCode] as [String]
    override func viewDidLoad() {
        super.viewDidLoad()
        // Get an instance of the AVCaptureDevice class to initialize a device object and provide the video as the media type parameter.
        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)
            captureMetadataOutput.metadataObjectTypes = supportedCodeTypes
            // 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 and top bar to the front
            view.bringSubview(toFront: messageLabel)
            view.bringSubview(toFront: topbar)
            // 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
        }
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    // MARK: - AVCaptureMetadataOutputObjectsDelegate Methods
    func metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], from connection: AVCaptureConnection) {
        // Check if the metadataObjects array is not nil and it contains at least one object.
        if metadataObjects.count == 0 {
            qrCodeFrameView?.frame = CGRect.zero
            messageLabel.text = "No QR/barcode is detected"
            return
        }
        // Get the metadata object.
        let metadataObj = metadataObjects[0] as! AVMetadataMachineReadableCodeObject
        if supportedCodeTypes.contains(where: { $0 == metadataObj.type }) {
            // If the found metadata is equal to the QR code metadata then update the status label's text and set the bounds
            let barCodeObject = videoPreviewLayer?.transformedMetadataObject(for: metadataObj)
            qrCodeFrameView?.frame = barCodeObject!.bounds
            if metadataObj.stringValue != nil {
                messageLabel.text = metadataObj.stringValue
            }
        }
    }
     }

我正在使用iOS版本9.3.5在iPod上测试它，并且代码在 Swift 3与Xcode 8.3.2。

Answer 1

在iOS 10.x metadataOutput上称为 captureOutput。更改名称和签名，它应该完美地工作：

func captureOutput(_ output: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!) {
   // func code
}