CGImageFromFile

gistfile1.m

CGImageRef CGImageFromFile (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((__bridge 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;
}