iOS 获取当前正在显示的ViewController

//获取当前屏幕显示的viewcontroller  
- (UIViewController *)getCurrentVC  
{  
    UIViewController *result = nil;  
      
    UIWindow * window = [[UIApplication sharedApplication] keyWindow];  
    if (window.windowLevel != UIWindowLevelNormal)  
    {  
        NSArray *windows = [[UIApplication sharedApplication] windows];  
        for(UIWindow * tmpWin in windows)  
        {  
            if (tmpWin.windowLevel == UIWindowLevelNormal)  
            {  
                window = tmpWin;  
                break;  
            }  
        }  
    }  
      
    UIView *frontView = [[window subviews] objectAtIndex:0];  
    id nextResponder = [frontView nextResponder];  
      
    if ([nextResponder isKindOfClass:[UIViewController class]])  
        result = nextResponder;  
    else  
        result = window.rootViewController;  
      
    return result;  
} 

2.获取当前屏幕中present出来的viewcontroller。

- (UIViewController *)getPresentedViewController  
{  
    UIViewController *appRootVC = [UIApplication sharedApplication].keyWindow.rootViewController;  
    UIViewController *topVC = appRootVC;  
    if (topVC.presentedViewController) {  
        topVC = topVC.presentedViewController;  
    }  
      
    return topVC;  
} 

    func rootViewCon() -> UIViewController {
        
        var topVC = UIApplication.shared.keyWindow?.rootViewController
        while topVC?.presentedViewController != nil {
            topVC = topVC?.presentedViewController!
        }
        
        return topVC!
    }