public function & GetField ($fieldName = '') {
		$result = NULL;
		if (isset($this->fields[$fieldName]))
			$result = & $this->fields[$fieldName];
		return $result;
	}
public function & GetField ($fieldName = '') {
		$result = NULL;
		if (isset($this->fields[$fieldName]))
			$result = & $this->fields[$fieldName];
		return $result;
	}
public function & GetField ( $ fieldName = '' ) { $ result = NULL ; if ( isset ( $ this -> fields [ $ fieldName ] ) ) $ result = & $ this -> fields [ $ fieldName ] ; return $ result ; }
Return form field instance by form field name if it exists, else return null;
@param string $fieldName
@return \MvcCore\Ext\Forms\Field|\MvcCore\Ext\Forms\IField|NULL
Return form field instance by form field name if it exists else return null ;