获取当前界面所对应视图控制器方法（封装方式：公共方法、Category由个人喜好自行斟酌）

- (UIViewController *)getCurrentViewController{
    
    UIViewController *currentViewController = [self getRootViewController];//获取根视图UIWindow.rootViewController

    while (1) {
        //使控制器呈现的方法有两种：UINavigationController的push 、 UIViewController的present
        if(currentViewController.presentedViewController){//判断当前控制器是否t以present方式呈现
            
            currentViewController = currentViewController.presentedViewController;
        }else if([currentViewController isKindOfClass:[UITabBarController class]]){//判断是否为UITabBarController对象
            
            UITabBarController *tabBarController =(UITabBarController *)currentViewController;
            currentViewController = tabBarController.selectedViewController;
        }else if([currentViewController isKindOfClass:[UINavigationController class]]){//判断是否为UINavigationControler对象
            
            UINavigationController* navigationController = (UINavigationController* )currentViewController;
            currentViewController = navigationController.visibleViewController;
        }else{
            
            NSUInteger childViewControllerCount = currentViewController.childViewControllers.count;
            if(childViewControllerCount > 0){//判断当前控制器是否有子控制器
                currentViewController = currentViewController.childViewControllers.lastObject;//取其子控制器栈顶对象
            }
            break;
        }
    }
    
    return currentViewController;
}

获取根视图控制器方法

- (UIViewController *)getRootViewController{
    
    UIWindow *window = [[[UIApplication sharedApplication] delegate] window];
    NSAssert(window, @"The window is empty");
    return window.rootViewController;
}