src/Message.php
public function content($content, $contentType = self::CONTENT_TYPE_HTML, $charset = null)
    {
        if (isset($this->params) && is_array($this->params)) {
            $content = $this->setDynamicContent($this->params, $content);
        }

        $this->getMessage()->setBody($content, $contentType, $charset);

        return $this;
    }
public function content($content, $contentType = self::CONTENT_TYPE_HTML, $charset = null)
    {
        if (isset($this->params) && is_array($this->params)) {
            $content = $this->setDynamicContent($this->params, $content);
        }

        $this->getMessage()->setBody($content, $contentType, $charset);

        return $this;
    }
Set the body of this message, either as a string, or as an instance of
{@link \Swift_OutputByteStream}.

@param mixed $content
@param string $contentType optional
@param string $charset     optional

@return $this

@see \Swift_Message::setBody()