iOS: Move debug background color setting and guard for release builds

Change-Id: Ie9131c3dfe16045805b37bf8af9381f4f9929da6
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>

src/plugins/platforms/ios/qiosviewcontroller.mm

@@ -48,6 +48,14 @@
 
 @implementation QIOSViewController
 
+- (void)viewDidLoad
+{
+#ifdef QT_DEBUG
+    if (!self.nibName)
+        self.view.backgroundColor = [UIColor magentaColor];
+#endif
+}
+
 -(BOOL)shouldAutorotate
 {
     // For now we assume that if the application doesn't listen to orientation

src/plugins/platforms/ios/qtmain.mm

@@ -58,9 +58,9 @@ extern int qt_main(int argc, char *argv[]);
     self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
     self.window.rootViewController = [[[QIOSViewController alloc] init] autorelease];
 
-    // Aid debugging during development
+#ifdef QT_DEBUG
     self.window.backgroundColor = [UIColor cyanColor];
-    self.window.rootViewController.view.backgroundColor = [UIColor magentaColor];
+#endif
 
     [self.window makeKeyAndVisible];