Qt ui in new class

[donex93]

macierz.h
@#ifndef MACIERZ_H
#define MACIERZ_H

#include <ui_mainwindow.h>

class Macierz
{
public:
Macierz(int wiersze, int kolumny);
void Utwoz();
private:

};

#endif // MACIERZ_H@

macierz.cpp

@#include "macierz.h"
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "macierz.h"

Macierz::Macierz(int wiersze, int kolumny)
{
this->wiersze = wiersze;
this->kolumny = kolumny;

}

void Macierz::Utwoz()
{
ui->pushButton->setEnabled(false);

}@

@ui->pushButton->setEnabled(false);@

do error: 'ui' was not declared in this scope

how i can repair this error ?
in "MainWindow" this

@ui->pushButton->setEnabled(false);@

work correctly