iOS: fix crash when application quits

An application will sometimes crash if the keyboard
is told to hide while the application is about to
quit. This patch will ensure that we set m_qioswindow
(and [UIView qwindow]) to 0 when the window is destroyed.
We also check this pointer before telling QUIView to
resign first responder when closing the keyboard. The
latter will fix the crash.

Task-number: QTBUG-35356

Change-Id: I934088beb7e877c5b33d96225cb215a8ffd4dbb2
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@digia.com>

1 files changed, 7 insertions, 3 deletions

diff --git a/src/plugins/platforms/ios/qioswindow.mm b/src/plugins/platforms/ios/qioswindow.mm
index 43f36e32e0..7b217e0bdc 100644
--- a/src/plugins/platforms/ios/qioswindow.mm
+++ b/src/plugins/platforms/ios/qioswindow.mm
@@ -341,7 +341,8 @@
     // Resigning first responed status means that the virtual keyboard was closed, or
     // some other view became first responder. In either case we clear the focus object to
     // avoid blinking cursors in line edits etc:
-    static_cast<QWindowPrivate *>(QObjectPrivate::get(m_qioswindow->window()))->clearFocusObject();
+    if (m_qioswindow)
+        static_cast<QWindowPrivate *>(QObjectPrivate::get(m_qioswindow->window()))->clearFocusObject();
     return [super resignFirstResponder];
 }
 
@@ -423,8 +424,10 @@
 
 - (QWindow *)qwindow
 {
-    if ([self isKindOfClass:[QUIView class]])
-        return static_cast<QUIView *>(self)->m_qioswindow->window();
+    if ([self isKindOfClass:[QUIView class]]) {
+        if (QIOSWindow *w = static_cast<QUIView *>(self)->m_qioswindow)
+            return w->window();
+    }
     return nil;
 }
 
@@ -461,6 +464,7 @@ QIOSWindow::~QIOSWindow()
     // cancellation of all touch events.
     [m_view touchesCancelled:0 withEvent:0];
 
+    m_view->m_qioswindow = 0;
     [m_view removeFromSuperview];
     [m_view release];
 }