//1.創(chuàng)建捕捉會話
AVCaptureSession *session = [[AVCaptureSession alloc]init];
self.session = session;
//2. 添加輸入設(shè)備
AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio];
AVCaptureDeviceInput *dinput = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil];
[session addInput:dinput];

// 3. 添加輸出設(shè)備

AVCaptureMetadataOutput *metadataOutput = [[AVCaptureMetadataOutput alloc  ]init];
//3.1這里實在主線程中設(shè)置的代理來獲取結(jié)果實際上要做實際的考慮
[metadataOutput setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
   [session addOutput:metadataOutput];
//3.2  添加到seesion 后才能添加輸出的類型
[metadataOutput setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode]];

 //4.添加輸出圖層
AVCaptureVideoPreviewLayer *preiewLayer =[AVCaptureVideoPreviewLayer layerWithSession:session];
preiewLayer.frame =self.view.bounds;
self.layer = preiewLayer;
[self.view.layer addSublayer:preiewLayer];
// 5開始掃描
[session startRunning];

pragma marke 掃描的代理方法 實現(xiàn)這個代理方法，在這里面獲取掃描的結(jié)果

• (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection{
  if(metadataObjects.count >0){
  NSLog(@"掃描到二維碼");
  // 獲取掃描結(jié)果
  AVMetadataMachineReadableCodeObject *object = [metadataObjects lastObject];
  NSLog(@"%@",object.stringValue);
  // 停止掃描
  [self.session stopRunning];
  [self.layer removeFromSuperlayer];
  }else{
  NSLog(@"沒有掃描到數(shù)據(jù)");
  }
  }