protected function getPrivateKey()
    {
        try {
            $privateKey = file_get_contents($this->privateKeyPath);
        } catch (\Exception $e) {
            $msg = 'Impossible to read the private key of the DKIM swiftmailer signer "%s"';

            throw new RuntimeException(sprintf($msg, $this->privateKeyPath));
        }

        return $privateKey;
    }
protected function getPrivateKey()
    {
        try {
            $privateKey = file_get_contents($this->privateKeyPath);
        } catch (\Exception $e) {
            $msg = 'Impossible to read the private key of the DKIM swiftmailer signer "%s"';

            throw new RuntimeException(sprintf($msg, $this->privateKeyPath));
        }

        return $privateKey;
    }
protected function getPrivateKey ( ) { try { $ privateKey = file_get_contents ( $ this -> privateKeyPath ) ; } catch ( \ Exception $ e ) { $ msg = 'Impossible to read the private key of the DKIM swiftmailer signer "%s"' ; throw new RuntimeException ( sprintf ( $ msg , $ this -> privateKeyPath ) ) ; } return $ privateKey ; }
Get the private key.

@throws RuntimeException When the private key cannot be read

@return string
Get the private key .