怎样去掉UIWebView 右侧的滚动条，和滚动时出界后的黑色背景

如题，隐藏滚动条和上下滚动时出边界的后面的黑色的背景

aWebView.backgroundColor=[UIColor clearColor];
   for (UIView *_aView in [aWebView subviews])
   {
    if ([_aView isKindOfClass:[UIScrollView class]])
       {
           [(UIScrollView *)_aView setShowsVerticalScrollIndicator:NO]; //右侧的滚动条

        for (UIView *_inScrollview in _aView.subviews)
           {

               if ([_inScrollview isKindOfClass:[UIImageView class]])
               {
                   _inScrollview.hidden = YES;  //上下滚动出边界时的黑色的图片
               }
        }
    }
}