用于捕获二维码的代码在 Xcode8 和 Swift3 中似乎运行不佳

Question

我正在尝试在 Swift3 和 iOS 10 beta 设备中使用 AVCaptureMetadataOutputObjectsDelegate 捕获二维码。

但是captureOutput当QR码被设备的摄像头实际捕获时，函数不会被调用。

有人对此有解决方案吗？如果是这样，请告诉我如何修复和正常工作。

谢谢，

import UIKit
import AVFoundation

class ViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {

  override func viewDidLoad() {
    super.viewDidLoad()

    let mySession: AVCaptureSession! = AVCaptureSession()
    let devices = AVCaptureDevice.devices()
    var myDevice: AVCaptureDevice!

    for device in devices! {
      if((device as AnyObject).position == AVCaptureDevicePosition.back){
        myDevice = device as! AVCaptureDevice
      }
    }

    let myVideoInput = try! AVCaptureDeviceInput.init(device: myDevice)

    if mySession.canAddInput(myVideoInput) {
      mySession.addInput(myVideoInput)
    }

    let myMetadataOutput: AVCaptureMetadataOutput! = AVCaptureMetadataOutput()

    if mySession.canAddOutput(myMetadataOutput) {
      mySession.addOutput(myMetadataOutput)
      myMetadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
      myMetadataOutput.metadataObjectTypes = [AVMetadataObjectTypeQRCode]
    }

    let myVideoLayer = AVCaptureVideoPreviewLayer.init(session: mySession)
    myVideoLayer?.frame = self.view.bounds
    myVideoLayer?.videoGravity = AVLayerVideoGravityResizeAspectFill
    self.view.layer.addSublayer(myVideoLayer!)

    mySession.startRunning()
  }


  // MARK: - AVCaptureMetadataOutputObjectsDelegate

  // This function is not called despite capturing QR code  
  func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, from connection: AVCaptureConnection!) {
    if metadataObjects.count > 0 {
      let qrData: AVMetadataMachineReadableCodeObject  = metadataObjects[0] as! AVMetadataMachineReadableCodeObject
      print("\(qrData.type)")
      print("\(qrData.stringValue)")

    }
  }

}

Answer 1

在Swift3中实现AVCaptureMetadataOutputObjectsDelegate的方法头变成了这样：

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

[AnyObject] -> [Any]，我没有检查你代码的其他部分，但至少，你需要解决这个问题。

Answer 2

SWIFT 3: 在我的例子中，这段代码解决了问题：

旧的错误代码

private func captureOutput(captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, fromConnection connection: AVCaptureConnection!) {
    for item in metadataObjects {
        if let metadataObject = item as? AVMetadataMachineReadableCodeObject {
            if metadataObject.type == AVMetadataObjectTypeQRCode {
                print("QR Code: \(metadataObject.stringValue)")
            }
        }
    }
}

正确答案

func captureOutput(_ captureOutput: AVCaptureOutput!,
                   didOutputMetadataObjects metadataObjects: [Any]!,
                   from connection: AVCaptureConnection!) {
    for item in metadataObjects {
        if let metadataObject = item as? AVMetadataMachineReadableCodeObject {
            if metadataObject.type == AVMetadataObjectTypeQRCode {
                print("QR Code: \(metadataObject.stringValue)")
            }
        }
    }

}

Answer 3

Swift中的委托方法4

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

用于捕获二维码的代码在 Xcode8 和 Swift3 中似乎运行不佳

Code for capturing QR Code doesn't seem working well in Xcode8 and Swift3

avfoundation

ios

swift

swift3

ios10