src/Primitive/String/String.php
public function isUuid($uuid = null)
    {
        if (is_null($uuid)) $uuid = $this->string;

        $uuid = $this->retrieveValue($uuid);

        return (bool) preg_match(
            '/^\{?[0-9a-f]{8}\-?[0-9a-f]{4}\-?[0-9a-f]{4}\-?[0-9a-f]{4}\-?[0-9a-f]{12}\}?$/i', $uuid
        );
    }
public function isUuid($uuid = null)
    {
        if (is_null($uuid)) $uuid = $this->string;

        $uuid = $this->retrieveValue($uuid);

        return (bool) preg_match(
            '/^\{?[0-9a-f]{8}\-?[0-9a-f]{4}\-?[0-9a-f]{4}\-?[0-9a-f]{4}\-?[0-9a-f]{12}\}?$/i', $uuid
        );
    }
Check if String is Unique User Identifier generated by String.
If optional $uuid argument is specified, it will check it not inner value.

@param null|string|StringContract $uuid
@return bool