Facebook PHP upload file from memory

I'm reading an image from my S3 bucket in AWS and want to upload it to Facebook.

This is the reading function:

/**
 * Get a file from the s3 storage
 */
private function uploadPicture() {
    $picture = new FacebookPicture();
    $file = $this->s3Manager->getFile($this->subEndPoint,$this->verb);
    $picture->pictureContent = $file["Body"];
    $facebookAlbum = new FacebookAlbum();
    $facebookAlbum->album = new Album();
    $facebookAlbum->album->facebookAccessToken = "myAccessToken";
    $facebookAlbum->id = "myAlbumId";
    $facebookManager = new FacebookManager();
    $facebookManager->uploadPicture($facebookAlbum,$picture);
}

This is the uploading to Facebook function

/**
 * @param $facebookAlbum FacebookAlbum the album to upload the picture to
 * @param $picture FacebookPicture the picture to upload
 */
public function uploadPicture($facebookAlbum,$picture)
{
    $this->facebook->setAccessToken($facebookAlbum->album->facebookAccessToken);
    $this->facebook->setFileUploadSupport(true);
    $args = array();
    $args["message"] = $picture->description;
    $args["source"] = "@" . $picture->pictureContent;
    $data = $this->facebook->api('/'. $facebookAlbum->id . '/photos', 'post', $args);
    var_dump($data);
}

I keep getting :

curl_setopt_array(): The usage of the @filename API for file uploading is deprecated. Please use the CURLFile class instead in <b>acebook-php-sdk-master/src/base_facebook.php</b> on line <b>1005</b><br />

I think that the problem is that the image content is saved in the memory.

How can I use the variable in my memory in order to post it to Facebook ?