Add QTimer::singleShot() wrappers to display startup dialogs on macOS

lib/utils/backup.cpp

@@ -8,13 +8,18 @@
 
 #include <obs-frontend-api.h>
 #include <obs-module.h>
-#include <QFileDialog>
-#include <QTextStream>
 #include <util/config-file.h>
 
+#include <QFileDialog>
+#include <QMainWindow>
+#include <QTextStream>
+#include <QTimer>
+
+#include <thread>
+
 namespace advss {
 
-void AskForBackup(const QString &json)
+static void showBackupDialogs(const QString &json)
 {
 	const bool backupWasConfirmed = DisplayMessage(
 		obs_module_text("AdvSceneSwitcher.askBackup"), true, false);
@@ -42,6 +47,40 @@ void AskForBackup(const QString &json)
 	out << json;
 }
 
+void AskForBackup(obs_data_t *settings)
+{
+	// This function is called while the plugin settings are being loaded.
+	// Blocking at this stage can cause issues such as OBS failing to start
+	// or crashing.
+	// Therefore, we ask the user whether they want to back up the settings
+	// asynchronously.
+	//
+	// On macOS, an additional QTimer::singleShot wrapper is required for
+	// this to work correctly.
+
+	auto json = obs_data_get_json(settings);
+	static QString jsonQString = json ? json : "";
+
+	static const auto askForBackupWrapper = [](void *) {
+#ifdef __APPLE__
+		QTimer::singleShot(0,
+				   static_cast<QMainWindow *>(
+					   obs_frontend_get_main_window()),
+				   []() {
+#endif
+					   showBackupDialogs(jsonQString);
+#ifdef __APPLE__
+				   });
+#endif
+	};
+
+	std::thread t([]() {
+		obs_queue_task(OBS_TASK_UI, askForBackupWrapper, nullptr,
+			       false);
+	});
+	t.detach();
+}
+
 void BackupSettingsOfCurrentVersion()
 {
 	auto sceneCollectionName = obs_frontend_get_current_scene_collection();