iOS: Ensure UIApplicationMain is started before QApplication by wrapping main()

For the typical Qt app the developer will have an existing main() that
looks something like:

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);

    return app.exec();
}

To support this, we provide our own 'main' function in the
qtmain static library that we link into the application, which calls
UIApplicationMain and redirects to the 'main' function of the application
after the event loop has started spinning. For this to work, the applications
'main' function needs to manually be renamed 'qt_main' for now. In a later
patch, this renaming will happen automatically by redefining main from either a
header file, or more likely, from the Makefile created by qmake.

For the case of an iOS developer wanting to use Qt in their existing app
the main will look something like:

int main(int argc, char *argv[])
{
    @autoreleasepool {
        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
    }
}

This is supported right now by just linking in libqios.a without libqiosmain.a.
QGuiApplication should then be created e.g inside the native apps application
delegate (but QGuiApplication::exec should not be called).

In the future, we plan to but use a wrapper library that
brings in all the Qt dependencies into one single static library. This library will
not link against qtmain, so there won't be a symbol clash if the -ObjC linker option
is used. We should then add the required magic to the future Objective-C convenience
wrapper for QML to bring up a QGuiApplication, which would allow using Qt from
storyboards and NIBs. This would also be the place to inject our own
application delegate into the mix, while proxying the delegate callbacks
to the user's application delegate.

Change-Id: Iba5ade114b27216be8285f36100fd735a08b9d59
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@digia.com>
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>

1 files changed, 69 insertions, 0 deletions

diff --git a/src/plugins/platforms/ios/plugin.mm b/src/plugins/platforms/ios/plugin.mm
new file mode 100644
index 0000000000..3701ac7e28
--- /dev/null
+++ b/src/plugins/platforms/ios/plugin.mm
@@ -0,0 +1,69 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/
+**
+** This file is part of the plugins of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** GNU Lesser General Public License Usage
+** This file may be used under the terms of the GNU Lesser General Public
+** License version 2.1 as published by the Free Software Foundation and
+** appearing in the file LICENSE.LGPL included in the packaging of this
+** file. Please review the following information to ensure the GNU Lesser
+** General Public License version 2.1 requirements will be met:
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights. These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU General
+** Public License version 3.0 as published by the Free Software Foundation
+** and appearing in the file LICENSE.GPL included in the packaging of this
+** file. Please review the following information to ensure the GNU General
+** Public License version 3.0 requirements will be met:
+** http://www.gnu.org/copyleft/gpl.html.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms and
+** conditions contained in a signed written agreement between you and Nokia.
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <qpa/qplatformintegrationplugin.h>
+#include <qpa/qplatformthemeplugin.h>
+#include "qiosintegration.h"
+
+QT_BEGIN_NAMESPACE
+
+class QIOSIntegrationPlugin : public QPlatformIntegrationPlugin
+{
+    Q_OBJECT
+        Q_PLUGIN_METADATA(IID "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.1" FILE "ios.json")
+    public:
+        QPlatformIntegration *create(const QString&, const QStringList&);
+};
+
+QPlatformIntegration * QIOSIntegrationPlugin::create(const QString& system, const QStringList& paramList)
+{
+    Q_UNUSED(paramList);
+    if (system.toLower() == "ios")
+        return new QIOSIntegration;
+
+    return 0;
+}
+
+QT_END_NAMESPACE
+
+#include "plugin.moc"
+
+Q_IMPORT_PLUGIN(QIOSIntegrationPlugin)