Re: [Solved] Help! Can't get QContactManager to work at all
 

You have to add this line in the .cpp file

QTM_USE_NAMESPACE

like this:

#include <QContactManager>

QTM_USE_NAMESPACE

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