macOS: Keep reference to NSScreen via index instead of pointer

Manual revert of 73e68a9c0f8b6, which was flawed. macOS can, and will,
dealloc and realloc NSScreen instances for a given screen index, for
example when deallocing an NSWindow, which has the screen as an
auxiliary resource. This is also documented for +[NSScreen screens],
which states that "The array should not be cached".

Task-number: QTBUG-58128
Change-Id: I926513a26cb7af52acd7fc5ee9380ef29ede65e6
Reviewed-by: Robin Burchell <robin.burchell@crimson.no>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoaintegration.h b/src/plugins/platforms/cocoa/qcocoaintegration.h
index 5cf8e7d237..a3c375881d 100644
--- a/src/plugins/platforms/cocoa/qcocoaintegration.h
+++ b/src/plugins/platforms/cocoa/qcocoaintegration.h
@@ -61,7 +61,7 @@ QT_BEGIN_NAMESPACE
 class QCocoaScreen : public QPlatformScreen
 {
 public:
-    QCocoaScreen(NSScreen *screen);
+    QCocoaScreen(int screenIndex);
     ~QCocoaScreen();
 
     // ----------------------------------------------------
@@ -84,7 +84,7 @@ public:
     // ----------------------------------------------------
     // Additional methods
     void setVirtualSiblings(const QList<QPlatformScreen *> &siblings) { m_siblings = siblings; }
-    NSScreen *nsScreen() const;
+    NSScreen *nativeScreen() const;
     void updateGeometry();
 
     QPointF mapToNative(const QPointF &pos) const { return flipCoordinate(pos); }
@@ -97,7 +97,7 @@ private:
     QRectF flipCoordinate(const QRectF &rect) const;
 
 public:
-    NSScreen *m_nsScreen;
+    int m_screenIndex;
     QRect m_geometry;
     QRect m_availableGeometry;
     QDpi m_logicalDpi;