//生成二維碼
- (UIImage *)createQRCodeWithUrl:(NSString *)url {
    // 1. 創(chuàng)建一個二維碼濾鏡實例(CIFilter)
    CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    // 濾鏡恢復(fù)默認(rèn)設(shè)置
    [filter setDefaults];

    // 2. 給濾鏡添加數(shù)據(jù)
    NSString *string = url;
    NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];
    // 使用KVC的方式給filter賦值
    [filter setValue:data forKeyPath:@"inputMessage"];

    // 3. 生成二維碼
    CIImage *image = [filter outputImage];
    // 轉(zhuǎn)成高清格式
    UIImage *qrcode = [self createNonInterpolatedUIImageFormCIImage:image withSize:200];
    // 添加logo
    qrcode = [self drawImage:imageName(@"logo") inImage:qrcode];
    return qrcode;
}

// 將二維碼轉(zhuǎn)成高清的格式
- (UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat) size {

    CGRect extent = CGRectIntegral(image.extent);
    CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));

    // 1.創(chuàng)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到圖片
    CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
    CGContextRelease(bitmapRef);
    CGImageRelease(bitmapImage);
    return [UIImage imageWithCGImage:scaledImage];
}

// 添加logo
- (UIImage *)drawImage:(UIImage *)newImage inImage:(UIImage *)sourceImage {
    CGSize imageSize; //畫的背景 大小
    imageSize = [sourceImage size];
    UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0.0);
    [sourceImage drawAtPoint:CGPointMake(0, 0)];
    //獲得 圖形上下文
    CGContextRef context=UIGraphicsGetCurrentContext();
    //畫 自己想要畫的內(nèi)容(添加的圖片)
    CGContextDrawPath(context, kCGPathStroke);
    // 注意logo的尺寸不要太大,否則可能無法識別
    CGRect rect = CGRectMake(imageSize.width / 2 - 25, imageSize.height / 2 - 25, 50, 50);
//    CGContextAddEllipseInRect(context, rect);
    CGContextClip(context);

    [newImage drawInRect:rect];

    //返回繪制的新圖形
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}