二维码

// 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:300];
 /**
 *  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");
    }
}