// 二维码的生成

// 1、创建过滤器
CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];

// 2、恢复滤镜的默认属性
[filter setDefaults];

// 3、设置内容
NSString *str = @"这是一个二维码的生成结果";
NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];

// 使用KVO设置属性
[filter setValue:data forKey:@"inputMessage"];

// 4、获取输出文件
CIImage *outputImage = [filter outputImage];

// 5、显示二维码
self.imageView.image = [UIImage imageWithCIImage:outputImage];

/**
 *  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];
}

#import "ViewController.h"
#import <AVFoundation/AVFoundation.h>

@interface ViewController () <AVCaptureMetadataOutputObjectsDelegate>
/**显示图层*/
@property (nonatomic, strong) AVCaptureVideoPreviewLayer *layer;
/**捕捉会话*/
@property (nonatomic, strong) AVCaptureSession *session;

@end

@implementation ViewController


- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    // 二维码的扫描
    // 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];
}

/**
 *	实现output的回调方法
 */
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{
    // 数组metadataObjects中存放结果数据
    if (metadataObjects.count > 0) {
        // 获取最终的读取结果
        AVMetadataMachineReadableCodeObject *object = [metadataObjects lastObject];
        NSLog(@"%@",object.stringValue);
        [self.session stopRunning];
        [self.layer removeFromSuperlayer];
    }
    else
    {
        NSLog(@"没有扫描到数据");
    }
}
@end