iOS: add convenience function to get to the root QIOSViewController

It seems that we need to access our view controller from many
places, and the syntax to do so is tricky to remember. So lets
just add it to our global functions, with the added bonus of a
using a little cache.

Note: many of these functions could be made inline, but since one
concern of the plugin will be the end size of the app, I prefer
to trade size for speed at this point. We can always change this
later.

Change-Id: I578ea9ae8218d23d635b7728a930763ca53c4eaa
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@digia.com>

src/plugins/platforms/ios/qiosglobal.h

@@ -47,9 +47,13 @@
 #import <QtGui/qguiapplication.h>
 #import "qiosscreen.h"
 
+@class QIOSViewController;
+
 QT_BEGIN_NAMESPACE
 
 bool isQtApplication();
+QIOSViewController *rootViewController();
+
 CGRect toCGRect(const QRect &rect);
 QRect fromCGRect(const CGRect &rect);
 Qt::ScreenOrientation toQtScreenOrientation(UIDeviceOrientation uiDeviceOrientation);

src/plugins/platforms/ios/qiosglobal.mm

@@ -41,6 +41,7 @@
 
 #include "qiosglobal.h"
 #include "qiosapplicationdelegate.h"
+#include "qiosviewcontroller.h"
 #include <QtGui/qscreen.h>
 
 QT_BEGIN_NAMESPACE
@@ -57,6 +58,13 @@ bool isQtApplication()
     return isQt;
 }
 
+QIOSViewController *rootViewController()
+{
+    static QIOSViewController *c = isQtApplication() ?
+        static_cast<QIOSViewController *>([UIApplication sharedApplication].delegate.window.rootViewController) : nil;
+    return c;
+}
+
 CGRect toCGRect(const QRect &rect)
 {
     return CGRectMake(rect.x(), rect.y(), rect.width(), rect.height());

src/plugins/platforms/ios/qiosscreen.mm

@@ -44,6 +44,7 @@
 #include "qioswindow.h"
 #include <qpa/qwindowsysteminterface.h>
 #include "qiosapplicationdelegate.h"
+#include "qiosviewcontroller.h"
 
 #include <sys/sysctl.h>
 
@@ -141,8 +142,7 @@ QIOSScreen::QIOSScreen(unsigned int screenIndex)
 
     if (isQtApplication()) {
         // When in a non-mixed environment, let QScreen follow the current interface orientation:
-        UIViewController *controller = [UIApplication sharedApplication].delegate.window.rootViewController;
-        setPrimaryOrientation(toQtScreenOrientation(controller.interfaceOrientation));
+        setPrimaryOrientation(toQtScreenOrientation(rootViewController().interfaceOrientation));
     }
 
     [pool release];

src/plugins/platforms/ios/qioswindow.mm

@@ -197,7 +197,7 @@ QIOSWindow::QIOSWindow(QWindow *window)
     , m_devicePixelRatio(1.0)
 {
     if (isQtApplication())
-        [[UIApplication sharedApplication].delegate.window.rootViewController.view addSubview:m_view];
+        [rootViewController().view addSubview:m_view];
 
     setWindowState(window->windowState());