Presented view controller place under presenting view controller

Question

I build a native iOS framework, which imported to a Unity project, to manage game account (login, logout, signup,...). When I call framework method to show login screen, it's presented but place under presenting view controller.

- (void)showViewController:(UIViewController *)controller {
    UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:controller];
    nav.navigationBarHidden = YES;
   [nav setModalPresentationStyle: UIModalPresentationOverCurrentContext];
   [[UIViewController topMostController] presentViewController:nav animated:YES completion: nil];
}
+ (UIViewController*) topMostController {
    UIViewController *topController = [UIApplication sharedApplication].keyWindow.rootViewController;
    while (topController.presentedViewController) {
      topController = topController.presentedViewController;
    }
    return topController;
}

topMostController return UnityDefaultViewController (it's also rootViewController of keyWindow), and input of showViewController is my SigninViewController, why it's place under UnityDefaultViewController? I have imported this framework to a few Unity game before, but this is the first time I saw this issue.

[Update] After review code, there is some line of code which generated by Unity engine (my Unity dev guy said that) cause that issue:

- (void)showGameUI
{
   ...
   [_window addSubview: _rootView]; //this line cause the issue
   _window.rootViewController = _rootController;
   [_window bringSubviewToFront: _rootView];
   ...
}

Can anyone confirm these line of code are generated by Unity engine? I have tried to comment that line, issue gone and I haven't found other issue yet, but is that ok?

Answer 1

After many hours, finally I fixed it by changing presentation style from UIModalPresentationOverCurrentContext to UIModalPresentationOverFullScreen.