import AVFoundation//獲取攝像設備let device = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)do {  //創建輸入,輸出流  let input = try AVCaptureDeviceInput.init(device: device)  let output = AVCaptureMetadataOutput()  output.rectOfInterest = CGRect(x: 0.1, y: 0, width: 0.9, height: 1)  //設置代理,并且在主線程刷新  output.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)  //初始化鏈接對象 / 高質量采集率  session.canSetSessionPreset(AVCaptureSessionPresetHigh)  session.addInput(input)  session.addOutput(output)  //先添加輸入輸出流,后設置支持的掃碼所支持的格式,不然報錯如下:Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[AVCaptureMetadataOutput setMetadataObjectTypes:] Unsupported type found - use -availableMetadataObjectTypes'  //http://stackoverflow.com/questions/31063846/avcapturemetadataoutput-setmetadataobjecttypes-unsupported-type-found  //設置掃碼支持的編碼格式  output.metadataObjectTypes = [AVMetadataObjectTypeQRCode,AVMetadataObjectTypeEAN13Code,AVMetadataObjectTypeEAN8Code, AVMetadataObjectTypeCode128Code]  let layer = AVCaptureVideoPreviewLayer(session: session)  layer?.videoGravity = AVLayerVideoGravityResizeAspectFill  layer?.frame = view.layer.bounds  view.layer.insertSublayer(layer!, at: 0)  //開始捕捉  session.startRunning()} catch let error as NSError {  print("errorInfo/(error.domain)")}/// 實現代理方法extension ScanCodeController:AVCaptureMetadataOutputObjectsDelegate {  func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!) {    if metadataObjects.count > 0 {      session.stopRunning()      let object = metadataObjects[0]      let string: String = (object as AnyObject).stringValue      if let url = URL(string: string) {      if UIApplication.shared.canOpenURL(url) {        //去打開地址鏈接        _ = self.navigationController?.popViewController(animated: true)        UIApplication.shared.open(url)      } else {        //獲取非鏈接結果        let alertViewController = UIAlertController(title: "掃描結果", message: (object as AnyObject).stringValue, preferredStyle: .alert)        let actionCancel = UIAlertAction(title: "退出", style: .cancel, handler: { (action) in          _ = self.navigationController?.popViewController(animated: true)        })        let actinSure = UIAlertAction(title: "再次掃描", style: .default, handler: { (action) in          self.session.startRunning()        })        alertViewController.addAction(actionCancel)        alertViewController.addAction(actinSure)        self.present(alertViewController, animated: true, completion: nil)      }      }    }  }}