iOS 使用CIDetector扫描相册二维码、原生扫描

原生扫描

• iOS7之后，AVFoundation让我们终于可以使用原生扫描进行扫码了（二维码与条码皆可）AVFoundation可以让我们从设备中获取到输入流与输出流，从而获取二维码中包含的信息。
• 实现原生扫描非常简单。
  1.先导入AVFoundation框架。
  <AVFoundation/AVFoundation.h>
  2.接着设置代理，实现代理回调方法
  AVCaptureMetadataOutputObjectsDelegate
  3.然后创建几个类即可:
  设备 AVCaptureDevice
  捕捉会话 AVCaptureSession
  输入流 AVCaptureDeviceInput
  输出流 AVCaptureMetadataOutput
  预览图层 AVCaptureVideoPreviewLayer
• 下面是简单的代码实现示例

    NSError *error = nil;
    AVCaptureDevice *captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];//设备
    AVCaptureSession *session = [[AVCaptureSession alloc] init];//捕捉会话
    [session setSessionPreset:AVCaptureSessionPresetHigh];//设置采集率
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:captureDevice error:&error];//输入流
    AVCaptureMetadataOutput *output = [[AVCaptureMetadataOutput alloc] init];//输出流
    //添加到捕捉会话
    [session addInput:input];
    [session addOutput:output];
    //扫码类型：需要先将输出流添加到捕捉会话后再进行设置
    //这里只设置了可扫描二维码,有条码需要，在数组中继续添加即可
    [output setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode]];
    //输出流delegate,在主线程刷新UI
    [output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    AVCaptureVideoPreviewLayer *videoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];//预览
    videoPreviewLayer.frame = self.view.bounds;
    [self.view.layer insertSublayer:videoPreviewLayer atIndex:0];//添加预览图层
    //还可以设置扫描范围 output.rectOfInterest  不设置默认为全屏
    //开始扫描
    [session startRunning];

• 接着实现扫码成功的回调方法

  - (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection {
      NSString *content = @"";
      AVMetadataMachineReadableCodeObject *metadataObject = metadataObjects.firstObject;
      content = metadataObject.stringValue;//获取到二维码中的信息字符串
      //对此字符串进行处理(音效、网址分析、页面跳转等)
  }

• 我们还可以添加扫码成功后的声音与振动效果，提高用户体验

  - (void)playBeep{
    SystemSoundID soundID;
    AudioServicesCreateSystemSoundID((__bridge CFURLRef)[NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"滴-2"ofType:@"mp3"]], &soundID);
    AudioServicesPlaySystemSound(soundID);
    AudioServicesPlaySystemSound(kSystemSoundID_Vibrate);
  }

从相册获取二维码

• iOS8之后，可以使用CIDetector(CIDetector可用于人脸识别)进行图片解析，从而使我们可以便捷的从相册中获取到二维码。
• 1.调用系统相册，从系统相册中选取图片
  2.使用探测器(CIDetector)对选取的图片进行处理，取得图片二维码中包含的数据信息。
• 下面是简单的代码实现示例

  - (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 *)info
  {
    NSString *content = @"" ;
    //取出选中的图片
    UIImage *pickImage = info[UIImagePickerControllerOriginalImage];
    NSData *imageData = UIImagePNGRepresentation(pickImage);
    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;
    }
    //进行处理(音效、网址分析、页面跳转等)
  }