QThread - problems with it (beginner) - c++

Question

I try to use QThread, but I can't do it :(
My sample thread:
#include "worker.h"
#include "mainwindow.h"
#include <QDebug>
Worker::Worker() {}
Worker::~Worker() {
qDebug() << "Worker ends.";
}
void Worker::run() {
qDebug() << "Worker start.";
sleep(2);
emit finished();
}
And code on_btnStart_clicked():
Worker *worker = new Worker;
QThread *workerThread = new QThread(this);
connect(workerThread, SIGNAL(started()), worker, SLOT(start()));
connect(workerThread, SIGNAL(finished()), worker, SLOT(quit()));
worker->moveToThread(workerThread);
workerThread->start();
Worker starts, but never ends (if I close application, I get QThread: Destroyed while thread is still running.
Another problem - how I can transfer data between thread and my application? I want to use QThread for QLabel (example: timer). I can't find any good tutorial that I can complile without problems.
Anyone can help me?
And, if I can ask, how I can start thread like onCreate() for form? I want to create simple timer to count time of application running.
Regards

Answer 1

You should have a read through This article.
Look at the first code sample of the Qt 4.8 QThread documentation. It has many lines of boiler plate just to run some code in a thread. And the there is even a leak: the QThread is never going to quit and be destroyed.
The submitted patch has been accepted but the href link he forwards you to still shows the old code.
This patch snippet diff shows the valid approach on the right-side.
It shows both methods, sub-classing QThread and using QObject->Worker
You can use that as the sample to base your code on. Apply the approach that suit's your requirements as he mentions in the blog.