获取iOS应用中当前处于Activity状态的ViewController

- (UIViewController *)getCurrentVC
{
    UIViewController * curVC = 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]])
    {
        curVC = nextResponder;
    }
    else
    {
        UIViewController * appRootVC = window.rootViewController;
        UIViewController * topVC = appRootVC;
        curVC = topVC;
        if (topVC.presentedViewController)
        {
            curVC = topVC.presentedViewController;
        }
    }
    
    return curVC;
}