#import <CoreImage/CoreImage.h>

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{   // 1. 实例化二维码滤镜    CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];    // 2. 恢复滤镜的默认属性    [filter setDefaults];        // 3. 将字符串转换成NSData    NSString *dataStr = @"你想添加的数据";    NSData *data = http://www.mamicode.com/[dataStr dataUsingEncoding:NSUTF8StringEncoding];"inputMessage"];        // 5. 获得滤镜输出的图像    CIImage *outputImage = [filter outputImage];        // 6. 将CIImage转换成UIImage，并放大显示    self.imageView.image = [self createNonInterpolatedUIImageFormCIImage:outputImage withSize:200];    }/** *  根据CIImage生成指定大小的UIImage(高清的二维码图片) * *  @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];}