framework/web/Request.php
public function getHeader($name)
    {
        $name = mb_strtolower($name);
        return isset($this->headers[$name]) ? $this->headers[$name] : null;
    }
public function getHeader($name)
    {
        $name = mb_strtolower($name);
        return isset($this->headers[$name]) ? $this->headers[$name] : null;
    }
public function getHeader ( $ name ) { $ name = mb_strtolower ( $ name ) ; return isset ( $ this -> headers [ $ name ] ) ? $ this -> headers [ $ name ] : null ; }
Get header by name

@param string $name
@return string
Get header by name