How can I save an image (like using UIImageWriteToSavedPhotosAlbum() method) with a filename of my choice to the private/var folder?
Kenny, you had the answer! For illustration I always think code is more helpful.
//I do this in the didFinishPickingImage:(UIImage *)img method
NSData* imageData = UIImageJPEGRepresentation(img, 1.0);
//save to the default 100Apple(Camera Roll) folder.
[imageData writeToFile:@"/private/var/mobile/Media/DCIM/100APPLE/customImageFilename.jpg" atomically:NO];