iOS: Auto-release the UIWindow and root view-controller

They are retained properties.

Change-Id: Id1808d93fe30950fc05e41375f00183e098bff0b
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>

src/plugins/platforms/ios/qtmain.mm

@@ -55,10 +55,9 @@ extern int qt_main(int argc, char *argv[]);
 
 - (BOOL)application:(UIApplication *)application willFinishLaunchingWithOptions:(NSDictionary *)launchOptions
 {
-    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
-    QIOSViewController *controller = [[QIOSViewController alloc] init];
-    self.window.rootViewController = controller;
-    controller.view = [[UIView alloc] init];
+    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
+    self.window.rootViewController = [[[QIOSViewController alloc] init] autorelease];
+    self.window.rootViewController.view = [[UIView alloc] init];
 
     // Aid debugging during development
     self.window.backgroundColor = [UIColor cyanColor];