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:];
    id nextResponder = [frontView nextResponder];  

    if ([nextResponder isKindOfClass:[UIViewController class]])
        result = nextResponder;
    else
        result = window.rootViewController;  

    return result;
} 

.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!
    }