bonkers.m

- (BOOL)writeToURL:(NSURL *)absoluteURL ofType:(NSString *)typeName error:(NSError **)outError
{
    BOOL status = NO;
    CGImageDestinationRef dest = nil;
    
    /* Create a new CFStringRef containing a uniform type identifier (UTI) that is the equivalent
     of the passed file extension. */
    CFStringRef utiRef = UTTypeCreatePreferredIdentifierForTag(
                                                               kUTTagClassFilenameExtension,
                                                               (CFStringRef) typeName,
                                                               kUTTypeData
                                                               );
    if (utiRef==nil) 
    {
        goto bail;
    }

    /* Create an image destination writing to absoluteURL. */
    dest = CGImageDestinationCreateWithURL((CFURLRef)absoluteURL, utiRef, 1, nil);
    CFRelease(utiRef);
    
    if (dest==nil)
    {
        goto bail;        
    }

    /* The image snapshot associated with the document. */
    CGImageRef docImage = [self currentCGImage];
    if (docImage==nil)
    {
        goto bail;        
    }

    /* Set the image in the image destination to be our document image snapshot. */
    CGImageDestinationAddImage(dest, docImage, NULL);

    /* Writes image data to the URL associated with the image destination. */
    status = CGImageDestinationFinalize(dest);
    
bail:
    if (dest) 
    {
        CFRelease(dest);
    }
    return status;
}

- (BOOL)saveToURL:(NSURL *)absoluteURL ofType:(NSString *)typeName forSaveOperation:(NSSaveOperationType)saveOperation error:(NSError **)outError
{
    NSString *docTypeName = [absoluteURL pathExtension];
    /* Was an extension specified? */
    if ([docTypeName isEqualToString:@""]) 
    {
        /* No extension, so use jpeg. */
        docTypeName = @"jpg";
        return ([self writeToURL:[absoluteURL URLByAppendingPathExtension:docTypeName] ofType:docTypeName error:outError]);
    }

    return ([self writeToURL:absoluteURL ofType:docTypeName error:outError]);
}