关于前端:iOS142-获取top-viewcontroller

- (UIViewController *)mx_topVC{    UIWindow *kW = nil;    if (@available(iOS 13.0, *)) {        for (UIWindowScene* windowScene in [UIApplication sharedApplication].connectedScenes)        {            if (windowScene.activationState == UISceneActivationStateForegroundActive)            {                kW = windowScene.windows.firstObject;                break;            }        }    }else{        kW = [UIApplication sharedApplication].keyWindow;    }        UIViewController *topViewController = [kW rootViewController];        while (true) {        if (topViewController.presentedViewController)        {            topViewController = topViewController.presentedViewController;                    } else if ([topViewController isKindOfClass:[UINavigationController class]] && [(UINavigationController*)topViewController topViewController])        {            topViewController = [(UINavigationController *)topViewController topViewController];                    } else if ([topViewController isKindOfClass:[UITabBarController class]])        {            UITabBarController *tab = (UITabBarController *)topViewController;            topViewController = tab.selectedViewController;                    } else {            break;        }    }        return topViewController;}