You need to call trimComponentCache()
on QQmlEngine after you have set the Loaders source
property to an empty string. In other words:
helpLoader.source = "";
// call trimComponentCache() here!!!
helpLoader.source = "../dynamic.qml";
In order to do that, you'll need to expose some C++ object to QML which has a reference to your QQmlEngine (lots of examples in Qt and on StackOverflow to help with that).
trimComponentCache tells QML to forget about all the components it's not current using and does just what you want.
Update - explaining in a bit more detail:
For example, somewhere you define a class that takes a pointer to your QQmlEngine and exposes the trimComponentCache method:
class ComponentCacheManager : public QObject {
Q_OBJECT
public:
ComponentCacheManager(QQmlEngine *engine) : engine(engine) { }
Q_INVOKABLE void trim() { engine->trimComponentCache(); }
private:
QQmlEngine *engine;
};
Then when you create your QQuickView, bind one of the above as a context property:
QQuickView *view = new QQuickView(...);
...
view->rootContext()->setContextProperty(QStringLiteral("componentCache", new ComponentCacheManager(view->engine());
Then in your QML you can do something like:
helpLoader.source = "";
componentCache.trim();
helpLoader.source = "../dynamic.qml";