- (void)createLogoImage {    NSArray *filter = [CIFilter filterNamesInCategory:kCICategoryBuiltIn];    NSLog(@"%@", filter);    // 二维码过滤器    CIFilter *filterImage = [CIFilter filterWithName:@"CIQRCodeGenerator"];    // 将二位码过滤器设置为默认属性    [filterImage setDefaults];    // 将文字转化为二进制    NSData *dataImage = [@"mafeng" dataUsingEncoding:NSUTF8StringEncoding];    // 打印输入的属性    NSLog(@"%@", filterImage.inputKeys);    // KVC 赋值    [filterImage setValue:dataImage forKey:@"inputMessage"];    // 取出输出图片    CIImage *outputImage = [filterImage outputImage];    outputImage = [outputImage imageByApplyingTransform:CGAffineTransformMakeScale(20, 20)];    // 转化图片    UIImage *image = [UIImage imageWithCIImage:outputImage];        // 为二维码加自定义图片        // 开启绘图, 获取图片 上下文<图片大小>    UIGraphicsBeginImageContext(image.size);    // 将二维码图片画上去    [image drawInRect:CGRectMake(0, 0, image.size.width, image.size.height)];    // 将小图片画上去    UIImage *smallImage = [UIImage imageNamed:@"123.jpg"];    [smallImage drawInRect:CGRectMake((image.size.width - 100) / 2, (image.size.width - 100) / 2, 100, 100)];    // 获取最终的图片    UIImage *finalImage = UIGraphicsGetImageFromCurrentImageContext();    // 关闭上下文    UIGraphicsEndImageContext();    // 显示    self.imageview.image = finalImage;        }