长沙有哪个学校可以学网站建设网站制作模板

---

1. 从相机里扫描

1.1 申请相机权限

• 导入： import AVFoundation
• 在项目的 Info.plist 文件里添加 Privacy - Camera Usage Descriptio 描述申请使用相机权限。
• 查询相机权限： AVCaptureDevice.authorizationStatus(for: .video)
• 权限类型：AVAuthorizationStatus

notDetermined   未申请
restricted      受限制
denied          已拒绝
authorized      已授权

• 请求相机权限，系统弹出授权申请提示：

AVCaptureDevice.requestAccess(for: .video) { (status) in// handle request result
}

1.2 创建Scanner

• 获得设备:

 guard let device = AVCaptureDevice.default(for: .video) else {print("device error")return
}

• 创建input:

 let input: AVCaptureDeviceInput
do {input = try AVCaptureDeviceInput(device: device)
} catch {print("input error")return
}
if self.captureSession.canAddInput(input) {self.captureSession.addInput(input)
} else {print("session can't add input")return
}

• 创建 output:

let output = AVCaptureMetadataOutput()
if self.captureSession.canAddOutput(output) {// Tips: add output must before of set outputself.captureSession.addOutput(output)
} else {print("session can't add output")return
}// Set metadata identification type qr: QR code; Other: Barcode
// 设置扫描类型（qr：二维码，其他：条形码）
let hopeSupportTypes = [AVMetadataObject.ObjectType.qr,AVMetadataObject.ObjectType.ean13,AVMetadataObject.ObjectType.ean8,AVMetadataObject.ObjectType.pdf417]
var types: [AVMetadataObject.ObjectType] = []
for type in hopeSupportTypes {if output.availableMetadataObjectTypes.contains(type) {types.append(type)}
}
output.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
output.metadataObjectTypes = types        
output.rectOfInterest = CGRect(x: 0, y: 0,width: self.view.bounds.size.width,height: self.view.bounds.size.height)

• 设置预览视图:

let previewLayer = AVCaptureVideoPreviewLayer(session: self.captureSession)
previewLayer.frame = scanView.layer.bounds
previewLayer.videoGravity = .resizeAspectFill
scanView.layer.addSublayer(previewLayer)

1.3 开始扫描

Tips: 不能在主线程中扫描，否则会无法响应用户操作，导致卡死现象

DispatchQueue.global(qos: .userInitiated).async {self.captureSession.startRunning()
}

1.4 处理扫描结果

遵循 AVCaptureMetadataOutputObjectsDelegate 协议，实现扫描回调方法：

 func metadataOutput(_ output: AVCaptureMetadataOutput,didOutput metadataObjects: [AVMetadataObject],from connection: AVCaptureConnection) {guard let metadataObject = metadataObjects.first else {captureSession.stopRunning()return}guard let readableObject = metadataObject as? AVMetadataMachineReadableCodeObject else {print("as? AVMetadataMachineReadableCodeObject faliue")return}guard let stringValue = readableObject.stringValue else {print("stringValue faliue")return}AudioServicesPlaySystemSound(SystemSoundID(kSystemSoundID_Vibrate))print("scan result: \(stringValue)")   // print resultcaptureSession.stopRunning()
}

---

2. 从相册里扫描

2.1 获取相册权限

• 导入： import Photos
• 在项目的 Info.plist 文件里添加 Privacy - Photo Library Usage Description 描述申请访问相册权限。
• 查询相机权限：PHPhotoLibrary.authorizationStatus()
• 权限类型：PHAuthorizationStatus

notDetermined   未申请
restricted      受限制
denied          已拒绝
authorized      已授权
limited         已授权有限库访问

• 请求相册权限，系统弹出授权申请提示：

PHPhotoLibrary.requestAuthorization { (status) in// handle request result
}

2.2 打开相册

Tips: 打开相册必须在主线程中执行

 /// have photos permission
DispatchQueue.main.async {self.openPhotoLabrary()
}private func openPhotoLabrary() {let picker = UIImagePickerController()picker.title = "Photos"picker.delegate = selfpicker.allowsEditing = truepicker.sourceType = .photoLibrarypicker.navigationBar.barStyle = .defaultself.present(picker, animated: true, completion: nil)
}

2.3 获得选择结果

遵循 UIImagePickerControllerDelegate 和 UINavigationControllerDelegate 协议，并实现选中相片后触发的协议方法：

func imagePickerController(_ picker: UIImagePickerController,didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {dismiss(animated: true)guard let image = info[.originalImage] as? UIImage else {print("choose not image")return}parseBarCode(image: image)
}

2.4 解析相片中的二维码或条形码

导入：import Vision

 /// parse qrCode or barCode
private func parseBarCode(image: UIImage) {guard let cgimg = image.cgImage else {return}let request = VNDetectBarcodesRequest { req, err inif let error = err {print("parseBarCode error: \(error)")return}self.handleResults(req.results)}let handler = VNImageRequestHandler(cgImage: cgimg)do {try handler.perform([request])} catch {print("parseBarCode error: \(error)")}
}private func handleResults(_ result: [VNObservation]?) {guard let results = result, results.count > 0 else {print("parseBarCode result is nil: \(String(describing: result))")return}for result in results {self.handleResult(result)}
}private func handleResult(_ result: VNObservation) {guard let barcode = result as? VNBarcodeObservation,let value = barcode.payloadStringValue else {print("handleResult covert to string error: \(result)")return}if barcode.symbology == .qr {print("二维码: \(value)")} else {print("条形码: \(value), \(barcode.symbology.rawValue)")}
}

---

github demo

---

参考：
iOS16 Swift二维码/条形码扫描+相册获取识别