效果图：

图1 点击图中按钮 生成二维码

图2 生成二维码

核心代码：

- (UIImage *)createQRCodeOrBarCode:(BOOL)QROrBar code:(NSString *)code width:(CGFloat)width height:(CGFloat)height {
    if (!code || code.length == 0) {
         //code为nil, 不能生成二维码
        //code为@“”，可生成二维码，但扫描结果为：(null)，无意义
        return nil;
    }
    CIImage *returnImage;
    NSData *data = [code dataUsingEncoding:NSISOLatin1StringEncoding allowLossyConversion:NO];
    CIFilter *filter;
    if (QROrBar) {
        // 生成条形码
        //创建滤镜,对图像进行滤镜处理
        filter = [CIFilter filterWithName:@"CICode128BarcodeGenerator"];
        [filter setValue:data forKey:@"inputMessage"];
        returnImage = [filter outputImage];
    } else { 
        // 生成二维码
        filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
        [filter setValue:data forKey:@"inputMessage"];
        [filter setValue:@"H" forKey:@"inputCorrectionLevel"];
        returnImage = [filter outputImage];
    }
    //1.保持模糊效果
    return [UIImage imageWithCIImage:returnImage];
    /**
     // 2.消除模糊, extent 返回图片的frame
     CGFloat scaleX = width / returnImage.extent.size.width;
     CGFloat scaleY = height / returnImage.extent.size.height;
     CIImage *transformedImage = [returnImage imageByApplyingTransform:CGAffineTransformScale(CGAffineTransformIdentity, scaleX, scaleY)];
     return [UIImage imageWithCIImage:transformedImage];
     */
}

测试：

图3 按钮点击事件

图4 关联imageView属性