device = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)

do {
  try input = AVCaptureDeviceInput(device: device)
} catch let e as NSError {
  print(e.localizedDescription)
}

output = AVCaptureMetadataOutput()
// 设置代理在主线程中刷新
output?.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)

session = AVCaptureSession()
// 高质量采集率
session?.canSetSessionPreset(AVCaptureSessionPresetHigh)
session?.addOutput(output)
session?.addInput(input)

// 特别注意的地方：有效的扫描区域，定位是以设置的右顶点为原点。屏幕宽所在的那条线为y轴，屏幕高所在的线为x轴
let x = ((SCREENHeight - QRCodeWidth - topViewHeight) / 2.0) / SCREENHeight
let y = ((SCREENWidth - QRCodeWidth) / 2.0) / SCREENWidth
let width = QRCodeWidth / SCREENHeight
let height = QRCodeWidth / SCREENWidth
output?.rectOfInterest = CGRect(x: x, y: y, width: width, height: height)

output?.metadataObjectTypes = [AVMetadataObjectTypeQRCode, AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypeEAN8Code, AVMetadataObjectTypeCode128Code]

preview = AVCaptureVideoPreviewLayer(session: session)
preview?.videoGravity = AVLayerVideoGravityResizeAspectFill
preview?.frame = self.view.layer.bounds
self.view.layer.insertSublayer(preview!, at: 0)
session?.startRunning()

fileprivate func scanAnimation() -> CABasicAnimation {
   let scanNetAnimation = CABasicAnimation()
    // 沿Y轴运动
   scanNetAnimation.keyPath = "transform.translation.y"
   // 扫描框的高度，注意：这里是实际高度的相反数
   scanNetAnimation.byValue = QRCodeWidth
    // 动画的持续时间
   scanNetAnimation.duration = 1.5
   // 动画的重复次数
   scanNetAnimation.repeatCount = MAXFLOAT
   return scanNetAnimation
}

scanImageView?.layer.add(scanAnimation(), forKey: nil)

func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!) {
  if metadataObjects.count > 0 {
    session?.stopRunning()
    let metadataObject = metadataObjects[0] as AnyObject
    let stringValue: String = metadataObject.stringValue
    let vc = QRCodeResultViewController.instantiate()
    vc.resultStr = stringValue
    self.navigationController?.pushViewController(vc, animated: true)
  }
}

func webView(_ webView: UIWebView, shouldStartLoadWith request: URLRequest, navigationType: UIWebViewNavigationType) -> Bool {
  let requestURL = request.url
  if requestURL?.scheme == "http" || requestURL?.scheme == "https" || requestURL?.scheme == "mailto" && navigationType == .linkClicked {
//    UIApplication.shared.open(requestURL!, options: [:], completionHandler: nil)
    let svc = SFSafariViewController(url: requestURL!)
    self.present(svc, animated: true, completion: nil)
  }
  return true
}

open func open(_ url: URL, options: [String : Any] = [:], completionHandler completion: ((Bool) -> Swift.Void)? = nil)

let svc = SFSafariViewController(url: requestURL!)
self.present(svc, animated: true, completion: nil)