iOS二维码的生成和扫描

@property (strong,nonatomic)AVCaptureDevice * device;
@property (strong,nonatomic)AVCaptureDeviceInput * input;
@property (strong,nonatomic)AVCaptureMetadataOutput * output;
@property (strong,nonatomic)AVCaptureSession * session;
@property (strong,nonatomic)AVCaptureVideoPreviewLayer * layer; 
@property (nonatomic, strong)UIImageView *imageView;

// 1.创建过滤器
  CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
 
  // 2.恢复默认
  [filter setDefaults];
 
  // 3.给过滤器添加数据(正则表达式/账号和密码)
  NSString *dataString = @"http://www.520it.com";
  NSData *data = [dataString dataUsingEncoding:NSUTF8StringEncoding];
  [filter setValue:data forKeyPath:@"inputMessage"];
 
  // 4.获取输出的二维码
  CIImage *outputImage = [filter outputImage];
 
  //因为生成的二维码模糊，所以通过createNonInterpolatedUIImageFormCIImage:outputImage来获得高清的二维码图片
 
  // 5.显示二维码
  self.imageView.image = [self createNonInterpolatedUIImageFormCIImage:outputImage withSize:200];

/**
 * 根据CIImage生成指定大小的UIImage
 *
 * @param image CIImage
 * @param size 图片宽度
 */
- (UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat) size
{
  CGRect extent = CGRectIntegral(image.extent);
  CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));
 
  // 1.创建bitmap;
  size_t width = CGRectGetWidth(extent) * scale;
  size_t height = CGRectGetHeight(extent) * scale;
  CGColorSpaceRef cs = CGColorSpaceCreateDeviceGray();
  CGContextRef bitmapRef = CGBitmapContextCreate(nil, width, height, 8, 0, cs, (CGBitmapInfo)kCGImageAlphaNone);
  CIContext *context = [CIContext contextWithOptions:nil];
  CGImageRef bitmapImage = [context createCGImage:image fromRect:extent];
  CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone);
  CGContextScaleCTM(bitmapRef, scale, scale);
  CGContextDrawImage(bitmapRef, extent, bitmapImage);
 
  // 2.保存bitmap到图片
  CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
  CGContextRelease(bitmapRef);
  CGImageRelease(bitmapImage);
  return [UIImage imageWithCGImage:scaledImage];
}

// 1.创建捕捉会话
  AVCaptureSession *session = [[AVCaptureSession alloc] init];
  self.session = session;
 
  // 2.添加输入设备(数据从摄像头输入)
  AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
  AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil];
  [session addInput:input];
 
  // 3.添加输出数据(示例对象-->类对象-->元类对象-->根元类对象)
  AVCaptureMetadataOutput *output = [[AVCaptureMetadataOutput alloc] init];
  [output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
  [session addOutput:output];
 
  // 3.1.设置输入元数据的类型(类型是二维码数据)
  [output setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode]];
 
  // 4.添加扫描图层
  AVCaptureVideoPreviewLayer *layer = [AVCaptureVideoPreviewLayer layerWithSession:session];
  layer.frame = self.view.bounds;
  [self.view.layer addSublayer:layer];
  self.layer = layer;
 
  // 5.开始扫描
  [session startRunning];

// 当扫描到数据时就会执行该方法
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{
  if (metadataObjects.count > 0) {
    //获得扫描数据，最后一个时最新扫描的数据
    AVMetadataMachineReadableCodeObject *object = [metadataObjects lastObject];
    NSLog(@"%@", object.stringValue);
 
    // 停止扫描
    [self.session stopRunning];
 
    // 将预览图层移除
    [self.layer removeFromSuperlayer];
  } else {
    NSLog(@"没有扫描到数据");
  }
}