二维码扫描识别

首先给出本文小Deme
二维码的识别包括了两种方法，一种是打开摄像头扫描，一种是扫描相册的图片。
没事的时候写了小demo，接下来分析一下两种方法的实现：
第一种：通过识别相册的图片来识别二维码得到结果

- (void)choicePhoto {
    //调用相册
    UIImagePickerController *imagePicker = [[UIImagePickerController alloc]init];
    imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
    imagePicker.delegate = self;
    [self presentViewController:imagePicker animated:YES completion:nil];
}```

//选中图片的回调

• (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info {
  //取出选中的图片
  UIImage *pickImage = info[UIImagePickerControllerOriginalImage];
  self.image = [self alterImageSize:pickImage];
  [self dismissViewControllerAnimated:YES completion:^{
  [self codeRe];
  }];
  }

//利用苹果原生的来扫描二维码图片，有时图片太大会造成crash 所以在这里修改一下图片大小，这个问题之前也没遇到过，分享一下，也是学习了

• (UIImage *)alterImageSize:(UIImage *)originalImage {

  UIGraphicsBeginImageContext(originalImage.size);
  [originalImage drawInRect:CGRectMake(0, 0, originalImage.size.width, originalImage.size.height)];
  UIImage *NewImage = [UIImage imageWithCGImage:[UIGraphicsGetImageFromCurrentImageContext() CGImage]];
  return NewImage;
  }

• (void)codeRe {

  NSString *content = @"" ;
  NSData *imageData = UIImagePNGRepresentation(self.image);
  CIImage *ciImage = [CIImage imageWithData:imageData];
  //创建探测器
  CIDetector *detector = [CIDetector detectorOfType:CIDetectorTypeQRCode context:nil options:@{CIDetectorAccuracy: CIDetectorAccuracyLow}];
  NSArray *feature = [detector featuresInImage:ciImage];
  //取出探测到的数据
  for (CIQRCodeFeature *result in feature) {
  content = result.messageString;
  [self compelet:content];
  return;
  }
  }

识别成功以后给出提示音，停止摄像头，返回之前的页面通过代理传递识别结果。

• (void)compelet:(NSString *)resultMessageString {

  [self playBeep];
  [_session stopRunning];
  [self.navigationController popViewControllerAnimated:YES];
  if ([self.delegate respondsToSelector:@selector(searchReult:)]) {
  [self.delegate searchReult:resultMessageString];
  }
  }

//扫描成功时的提示音

• (void)playBeep{

  SystemSoundID soundID;
  AudioServicesCreateSystemSoundID((__bridge CFURLRef)[NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"6005"ofType:@"mp3"]], &soundID);
  AudioServicesPlaySystemSound(soundID);
  AudioServicesPlaySystemSound(kSystemSoundID_Vibrate);
  }

第二种：通过摄像头，也是常用的方法：

• (void)startSearch {

  NSError *error;
  //设备
  _device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
  //捕捉会话
  _session = [[AVCaptureSession alloc] init];
  //预先设置高质量的输入输出
  [_session setSessionPreset:AVCaptureSessionPresetHigh];
  //输入
  _input = [AVCaptureDeviceInput deviceInputWithDevice:_device error:&error];
  // 输出
  _output = [[AVCaptureMetadataOutput alloc] init];
  //添加输入与输出设备
  if ([_session canAddInput:_input]) {
  [_session addInput:_input];
  }
  if ([_session canAddOutput:_output]) {
  [_session addOutput:_output];
  }
  //设置代理并在主线程中刷新UI
  [_output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
  // _output.rectOfInterest = CGRectMake(100, 100, 100, 100);
  //设置扫描范围 output.rectOfInterest
  //设置扫描二维码等
  [_output setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode]];
  _previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:_session];//预览
  _previewLayer.frame = self.view.bounds;
  [self.view.layer insertSublayer:_previewLayer atIndex:0];//添加预览图层
  [_session startRunning];
  }

//判断相机是否可用

• (ErrorType)isCameraAvisible {

  BOOL flag;
  if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
  flag = YES;
  }else {
  flag = NO;
  }
  AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
  if (authStatus == AVAuthorizationStatusRestricted || authStatus ==AVAuthorizationStatusDenied)
  {
  flag = NO;
  }
  return flag;
  }

取消的时候dismiss回去

• (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {

  [picker dismissViewControllerAnimated:YES completion:nil];
  }

• (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection {

  NSString *conten = @"";
  AVMetadataMachineReadableCodeObject *metadataObject = metadataObjects.firstObject;
  conten = metadataObject.stringValue;
  if (conten.length > 1) {
  [self compelet:conten];
  }
  }

其实大部分是看的别人的代码，自己写的部分还有很多要完善的地方，就当学习啦！