[Qt5.8.0] Klawisze strzałek dlaczegoo nie działają?

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QKeyEvent>

namespace Ui {
    class MainWindow;
}

class MainWindow
    : public QMainWindow
{
    Q_OBJECT
   
public:
    explicit MainWindow( QWidget * parent = 0 );
    ~MainWindow();
    void pressKeyEvent( QKeyEvent * eve );
private:
    Ui::MainWindow * ui;
    QKeyEvent * event;
};

#endif // MAINWINDOW_H

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QKeyEvent>

MainWindow::MainWindow( QWidget * parent )
    : QMainWindow( parent )
     , ui( new Ui::MainWindow )
{
    ui->setupUi( this );
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::pressKeyEvent( QKeyEvent * eve )
{
    switch( eve->key() )
    {
    case Qt::Key_Left:
        ui->label->setText( "Nacisnieto strzalke w lewo" );
        break;
    case Qt::Key_Right:
        ui->label->setText( "Nacisnieto strzalke w prawo" );
        break;
    }
}