iOS: use an explicit pointer to qiosViewController

As it stood, we always relied on the root view controller
being a QIOSViewController if isQtApplication() returned
true. For mixed application, this might not always be true
as native code can choose to replace the root view controller
at times, or even rip it out, and place it as a child of
another (e.g UISplitViewController).
This change will give an extra protection against that.

Change-Id: I0cb85796a8b82f9037c32f9e85e04e1dc7aad8e2
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@digia.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/src/plugins/platforms/ios/qiosglobal.mm b/src/plugins/platforms/ios/qiosglobal.mm
index 5860078372..d26eca54e5 100644
--- a/src/plugins/platforms/ios/qiosglobal.mm
+++ b/src/plugins/platforms/ios/qiosglobal.mm
@@ -58,10 +58,14 @@ bool isQtApplication()
     return isQt;
 }
 
-QIOSViewController *rootViewController()
+QIOSViewController *qiosViewController()
 {
+    // If Qt controls the application, we have created a root view controller were we place top-level
+    // QWindows. Note that in a mixed native application, our view controller might later be removed or
+    // added as a child of another controller. To protect against that, we keep an explicit pointer to the
+    // view controller in cases where this is the controller we need to access.
     static QIOSViewController *c = isQtApplication() ?
-        static_cast<QIOSViewController *>([UIApplication sharedApplication].delegate.window.rootViewController) : nil;
+        static_cast<QIOSApplicationDelegate *>([UIApplication sharedApplication].delegate).qiosViewController : nil;
     return c;
 }