// 1.创建过滤器    CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];    // 2.恢复默认    [filter setDefaults];    // 3.添加二维码扫描出来的字符串    NSString *dataString = @"这是二维码扫出来的String";    NSData *data = http://www.mamicode.com/[dataString dataUsingEncoding:NSUTF8StringEncoding];"inputMessage"];    // 4.获取输出的二维码    CIImage *outputImage = [filter outputImage];    // 5.此时的CIImage格式的二维码会有些模糊，所以将CIImage转换成UIImage，并放大显示    self.imageView.image = [self createNonInterpolatedUIImageFormCIImage:outputImage withSize:200];**将CIImage转换成UIImage的方法**/** * 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];}

iOS-二维码生成