同じパスで setMainQmlFile が機能し、setSource が失敗するのはなぜですか?
QmlApplicationViewer viewer;
viewer.setOrientation(QmlApplicationViewer::ScreenOrientationAuto);
//viewer.setMainQmlFile(QLatin1String("qml/exQml02/main.qml")); // <-- works
viewer.setSource(QUrl("qrc:qml/exQml02/main.qml")); // <--- fails: qrc:qml/exQml02/main.qml: File not found