Time for action – downloading a file
First, create an instance of QNetworkAccessManager:
QNetworkAccessManager *m_nam = new QNetworkAccessManager(this);
Since QNetworkAccessManager inherits QObject, it takes a pointer to QObject, which is used as a parent. Thus, you do not have to take care of deleting the manager later on. Furthermore, one single instance of QNetworkAccessManager is enough for an entire application. So, either pass a pointer to the network access manager in your game or, for ease of use, create a singleton pattern and access the manager through that.
Tip
A singleton pattern ensures that a class is instantiated only once. The pattern is useful for accessing application-wide configurations or—as in our case—an instance of QNetworkAccessManager. On the wiki pages for http://www.qtcentre.org and http://www.qt-project.org, you will find examples for different singleton patterns. A simple template-based approach would look like this (as a header file):
template...
