iOS 二维码

-( void ) createERvvvWithContent:( NSString *)content{

    //content ：表示扫描二维码后显示的内容，传入URL可以跳转到相应的网页

     CIImage *ciImage = [ self createQRForString :content];

     UIImage *image = [ self  createNonInterpolatedUIImageFormCIImage :ciImage withSize : 500 ];   

     UIImage *resultImage = [ self imageBlackToTransparent :image  withRed : 0.93333 andGreen : 0.93333 andBlue : 0.93333 ]; // 生成的二维码图片

}

// 生成二维码

- ( CIImage *)createQRForString:(NSString*)qrString {

     NSData *stringData = [qrString  dataUsingEncoding : NSUTF8StringEncoding ];

     // 创建 filter

     CIFilter *qrFilter = [ CIFilter filterWithName : @"CIQRCodeGenerator" ];

     // 设置内容和纠错级别

     [qrFilter  setValue:stringData forKey:@"inputMessage"];

     [qrFilter  setValue:@"M" forKey:@"inputCorrectionLevel"];

     // 返回 CIImage

     return qrFilter. outputImage ;

}

// 将 CIImage 转换成 UIImage

- ( UIImage *)createNonInterpolatedUIImageFormCIImage:( CIImage *)image withSize:( CGFloat ) size {

     CGRect extent = CGRectIntegral (image. extent );

     CGFloat scale = MIN (size/ CGRectGetWidth (extent), size/ CGRectGetHeight (extent));

     // 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);

     // 保存 bitmap 到图片

     CGImageRef scaledImage = CGBitmapContextCreateImage (bitmapRef);

     CGContextRelease (bitmapRef);

     CGImageRelease (bitmapImage);

     return [ UIImage imageWithCGImage :scaledImage];

}

// 对二维码进行颜色填充

void ProviderReleaseData ( void *info, const void *data, size_t  size){

     free (( void *)data);

}

- ( UIImage *)imageBlackToTransparent:( UIImage *)image withRed:( CGFloat )red andGreen:( CGFloat )green andBlue:( CGFloat )blue{

     const int imageWidth = image. size . width ;

     const int imageHeight = image. size . height ;

     size_t       bytesPerRow = imageWidth * 4 ;

     uint32_t * rgbImageBuf = ( uint32_t *) malloc (bytesPerRow * imageHeight);

     CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB ();

     CGContextRef context = CGBitmapContextCreate (rgbImageBuf, imageWidth,imageHeight, 8 , bytesPerRow, colorSpace, kCGBitmapByteOrder32Little |  kCGImageAlphaNoneSkipLast );

            CGContextDrawImage (context, CGRectMake ( 0 , 0 , imageWidth, imageHeight), image. CGImage );

     // 遍历像素

     int  pixelNum = imageWidth * imageHeight;

     uint32_t  * pCurPtr = rgbImageBuf;

     for ( int i = 0 ; i < pixelNum; i++, pCurPtr++){

          if ((*pCurPtr & 0xFFFFFF00 ) < 0x99999900 )    // 将白色变成透明

              { // 改成下面的代码，会将图片转成想要的颜色

                uint8_t * ptr = ( uint8_t *)pCurPtr;

             ptr[ 3 ] = red; //0~255

             ptr[ 2 ] = green;

             ptr[ 1 ] = blue;

             }      

          else

             {      

               uint8_t * ptr = ( uint8_t *)pCurPtr;

             ptr[ 0 ] = 0 ;

            }

     }

     // 输出图片

     CGDataProviderRef dataProvider = CGDataProviderCreateWithData ( NULL , rgbImageBuf, bytesPerRow * imageHeight, ProviderReleaseData );

     CGImageRef imageRef = CGImageCreate (imageWidth, imageHeight, 8 , 32 , bytesPerRow, colorSpace, kCGImageAlphaLast | kCGBitmapByteOrder32Little , dataProvider,   NULL , true , kCGRenderingIntentDefault );

     CGDataProviderRelease (dataProvider);

     UIImage * resultUIImage = [ UIImage imageWithCGImage :imageRef];

     // 清理空间

     CGImageRelease (imageRef);

     CGContextRelease (context);

     CGColorSpaceRelease (colorSpace);

     return  resultUIImage;

}

// 图片压缩到指定大小

- ( UIImage *)imageByScalingAndCroppingForSize:( CGSize )targetSize SourceImge:( UIImage *)sourceImg

{

     UIImage  *sourceImage = sourceImg;

      UIImage *newImage = nil ;

     CGSize imageSize = sourceImage. size ;

     CGFloat width = imageSize. width ;

     CGFloat height = imageSize. height ;

     CGFloat targetWidth = targetSize. width ;

     CGFloat targetHeight = targetSize. height ;

     CGFloat scaleFactor = 0.0 ;

     CGFloat  scaledWidth = targetWidth;

     CGFloat  scaledHeight = targetHeight;

     CGPoint thumbnailPoint = CGPointMake ( 0.0 , 0.0 );

     if ( CGSizeEqualToSize (imageSize, targetSize) == NO )

    {

             CGFloat  widthFactor = targetWidth / width;

             CGFloat  heightFactor = targetHeight / height;

             if (widthFactor > heightFactor)

                  scaleFactor = widthFactor; // scale to fit height

             else

                   scaleFactor = heightFactor; // scale to fit width

             scaledWidth= width * scaleFactor;

           scaledHeight = height * scaleFactor; // center the image

            if (widthFactor > heightFactor)

           {

                thumbnailPoint. y = (targetHeight - scaledHeight) * 0.5 ;

          }

           else if (widthFactor < heightFactor)

          {     

              thumbnailPoint. x = (targetWidth - scaledWidth) * 0.5 ;

           }

     }

     UIGraphicsBeginImageContext (targetSize); // this will crop

     CGRect thumbnailRect = CGRectZero ;

    thumbnailRect. origin = thumbnailPoint;

    thumbnailRect. size . width = scaledWidth;

    thumbnailRect. size . height = scaledHeight;

    [sourceImage  drawInRect :thumbnailRect];

    newImage = UIGraphicsGetImageFromCurrentImageContext ();

     if (newImage == nil )

          NSLog ( @"could not scale image" );

     //pop the context to get back to the default

     UIGraphicsEndImageContext ();

     return  newImage;

}