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CGImageRef MyCreateCGImageFromFile (NSString* path) 
{ 
    // Get the URL for the pathname passed to the function. 
    NSURL             url = [NSURL fileURLWithPath:path]; 
    CGImageRef        myImage = NULL; 
    CGImageSourceRef  myImageSource; 
    CFDictionaryRef   myOptions = NULL; 
    CFStringRef       myKeys[2]; 
    CFTypeRef         myValues[2]; 

    // Set up options if you want them. The options here are for 
    // caching the image in a decoded form and for using floating-point 
    // values if the image format supports them. 
    myKeys[0] = kCGImageSourceShouldCache; 
    myValues[0] = (CFTypeRef)kCFBooleanTrue; 
    myKeys[1] = kCGImageSourceShouldAllowFloat; 
    myValues[1] = (CFTypeRef)kCFBooleanTrue; 

    // Create the dictionary 
    myOptions = CFDictionaryCreate(NULL, (const void **) myKeys, 
                   (const void **) myValues, 2, 
                   &kCFTypeDictionaryKeyCallBacks, 
                   & kCFTypeDictionaryValueCallBacks); 

    // Create an image source from the URL. 
    myImageSource = CGImageSourceCreateWithURL((CFURLRef)url, myOptions); 
    CFRelease(myOptions); 

    // Make sure the image source exists before continuing 
    if (myImageSource == NULL){ 
        fprintf(stderr, "Image source is NULL."); 
        return  NULL; 
    } 

    // Create an image from the first item in the image source. 
    myImage = CGImageSourceCreateImageAtIndex(myImageSource, 0, NULL); 
    CFRelease(myImageSource); 

    // Make sure the image exists before continuing 
    if (myImage == NULL){ 
         fprintf(stderr, "Image not created from image source."); 
         return NULL; 
    } 

    return myImage; 
} 

CGImageRef MyCreateThumbnailImageFromData (NSData * data, int imageSize) 
{ 
    CGImageRef        myThumbnailImage = NULL;
    CGImageSourceRef  myImageSource; 
    CFDictionaryRef   myOptions = NULL; 
    CFStringRef       myKeys[3]; 
    CFTypeRef         myValues[3]; 
    CFNumberRef       thumbnailSize; 

   // Create an image source from NSData; no options. 
   myImageSource = CGImageSourceCreateWithData((CFDataRef)data, 
                                               NULL); 

   // Make sure the image source exists before continuing. 
   if (myImageSource == NULL){ 
        fprintf(stderr, "Image source is NULL."); 
        return  NULL; 
   } 

   // Package the integer as a  CFNumber object. Using CFTypes allows you 
   // to more easily create the options dictionary later. 
   thumbnailSize = CFNumberCreate(NULL, kCFNumberIntType, &imageSize); 

   // Set up the thumbnail options. 
   myKeys[0] = kCGImageSourceCreateThumbnailWithTransform; 
   myValues[0] = (CFTypeRef)kCFBooleanTrue; 
   myKeys[1] = kCGImageSourceCreateThumbnailFromImageIfAbsent; 
   myValues[1] = (CFTypeRef)kCFBooleanTrue; 
   myKeys[2] = kCGImageSourceThumbnailMaxPixelSize; 
   myValues[2] = (CFTypeRef)thumbnailSize; 

   myOptions = CFDictionaryCreate(NULL, (const void **) myKeys, 
                   (const void **) myValues, 2, 
                   &kCFTypeDictionaryKeyCallBacks, 
                   & kCFTypeDictionaryValueCallBacks); 

  // Create the thumbnail image using the specified options. 
  myThumbnailImage = CGImageSourceCreateThumbnailAtIndex(myImageSource, 
                                          0, 
                                          myOptions); 
  // Release the options dictionary and the image source 
  // when you no longer need them. 
  CFRelease(thumbnailSize); 
  CFRelease(myOptions); 
  CFRelease(myImageSource); 

   // Make sure the thumbnail image exists before continuing. 
   if (myThumbnailImage == NULL){ 
         fprintf(stderr, "Thumbnail image not created from image source."); 
         return NULL; 
   } 

   return myThumbnailImage; 
}