//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;}