Qt timer: what is the best way to make a countdown?

Question

Qt

According to the functionality of the program, it assumes that the user will have 60 seconds to complete the action. You can also pause the counter. What is the best way to organize this: QTimer or a loop with a delay per second?
QTimer didn't really understand how to pause. There are many sources, but I could not do it.
And I didn't understand the delay. QThread or are there other ways? With QThread sleep also could not do it yet.
Please help.

Answer 1

DerClass::DerClass(QObject * parent)
    : QObject(parent)
    , mTimer(new QTimer(this)   
{
    connect(mTimer, SIGNAL(timeout()), this, SLOT(update()));
    mTimer->start(1000);
    mSecondsToEnd = 60;
}

DerClass::update()
{
    --mSecondsToEnd;
    if ( mSecondsToEnd > 0)
    {
        QStiring time = QString::number(mSecondsToEnd);
        ui->backTimerTextLabel->setText("Осталось " + time + " секунд" );
    }
    else
    {
        mTimer->stop();
        doWork();
    }
}

Answer 2

Head-on solution - use QTimer along with QTimerElapsed