Unload Plugin in Qt - qt

Question

Issue comes up when i try to unload plugin that is loaded and load a new one. So both plugins are loaded correctly, but when switching them (first is loaded, second is unloaded and viceversa) my app crashes. What can be the problem ?
First what i'm doing i try to unload a plugin stored into a QList of QPluginLoader, then i check (depdend on id(integer number) passed from a special menu for loading plugins ) what plugin to load. First load is well (first plugin is loaded, nothing at this point to unload) , second load (unload first plugin, second is loaded), at third load i get crash
void MainWindow::loadPluginUsingId (int plugin_id) {
foreach (QPluginLoader* pluginLoader, plugins) {
pluginLoader->unload();
delete pluginLoader;
}
switch (plugin_id) {
case 0 : {
foreach (QString fileName, pluginDir.entryList(QDir::Files)) {
if (fileName == fullNameOfPlugins.value(plugin_id)) {
QPluginLoader* pluginLoader = new QPluginLoader(pluginDir.absoluteFilePath(fileName));
QObject *plugin = pluginLoader->instance();
IndicatorInterface *indicator = qobject_cast<IndicatorInterface*>(plugin);
indicator->initIndicator();
plugins.append(pluginLoader);
}
}
}
break;
case 1 : {
foreach (QString fileName, pluginDir.entryList(QDir::Files)) {
if (fileName == fullNameOfPlugins.value(plugin_id)) {
QPluginLoader* pluginLoader = new QPluginLoader(pluginDir.absoluteFilePath(fileName));
QObject* plugin = pluginLoader->instance();
PlotterInterface *plotter = qobject_cast<PlotterInterface*>(plugin);
plotter->initPlotter();
plugins.append(pluginLoader);
}
}
}
break;
default :
break;
}
}

Answer 1

foreach (QPluginLoader* pluginLoader, plugins) {
pluginLoader->unload();
delete pluginLoader; // this could be your problem
}
You need to remove the dangling pointer from the plugins list. Failure to do that would result in what you're describing.
Try this:
while (!plugins.isEmpty()) {
QPluginLoader* pluginLoader = plugins.takeFirst();
pluginLoader->unload();
delete pluginLoader;
}