从矩形中删除activity的指示器

显示activity 指示器的代码：

UIActivityIndicatorView  *av = [[[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite] autorelease];
    av.frame=CGRectMake(0.5*winSize.width-winSize.width/4, 0.80*winSize.height , winSize.width/2, winSize.width/8);
    [av setBackgroundColor:[UIColor colorWithRed:0.23 green:0.23 blue:0.23 alpha:0.75]];
    av.layer.cornerRadius=4;
    av.tag  = 31000;
    [[[CCDirector sharedDirector]view]addSubview:av];
    [av startAnimating];

删除：

UIActivityIndicatorView *tmpimg = (UIActivityIndicatorView *)[[[CCDirector sharedDirector]view] viewWithTag:31000];
    if(tmpimg)
        [((UIView *)tmpimg) removeFromSuperview];

预期实现的是删除指示器本身。然后留下视图（av.frame) 的矩形框。

但是全删除了，不知道怎么实现我想要的功能？

设置t

av.hidesWhenStopped = YES;

可以在indicator停止之后隐藏它。不需要删除