@property (weak, nonatomic) IBOutlet UIImageView *imageView;

/**点击屏幕的时候显示二维码*/
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
  //1.创建滤镜
  CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];

  //2.恢复默认
  [filter setDefaults];

  //3.给滤镜添加数据
  NSString *dataString = @"http://www.xxx.com/theDesertIslandOutOfTheWorld/";
//  NSString *dataString = @"世俗孤岛";
  //将数据转换成NSData类型
  NSData *data = [dataString dataUsingEncoding:NSUTF8StringEncoding];
  //通过KVC设置滤镜的二维码输入信息
  [filter setValue:data forKey:@"inputMessage"];

  //4.获取输出的二维码图片（CIImage类型）
  CIImage *outImage = [filter outputImage];
  //将CIImage类型的图片装换成UIImage类型的图片
  UIImage *image = [UIImage imageWithCIImage:outImage];

  //5.显示二维码图片
  self.imageView.image = image;
}

@property (nonatomic, weak) AVCaptureSession *session;

@property (nonatomic, weak) AVCaptureVideoPreviewLayer *layer;

AVCaptureSession *session = [[AVCaptureSession alloc] init];
self.session = session;

//设置输入设备输入数据的类型（视频）
AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil];
[session addInput:input];

AVCaptureMetadataOutput *output = [[AVCaptureMetadataOutput alloc] init];
//设置代理
[output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
[session addOutput:output];

[output setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode]];

AVCaptureVideoPreviewLayer *layer = [AVCaptureVideoPreviewLayer layerWithSession:session];
layer.frame = self.view.bounds;
[self.view.layer addSublayer:layer];

[session startRunning];

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{
  if (metadataObjects.count > 0)
  {
    //获取输出端的信息
    AVMetadataMachineReadableCodeObject *object = [metadataObjects lastObject];
    NSLog(@"%@", object.stringValue);

    //停止扫描
    [self.session stopRunning];

    //将展示图层移除
    [self.layer removeFromSuperlayer];
  }
  else
  {
    NSLog(@"没有扫描到数据");
  }
}