How to assign separate memory spaces of same type of class
add{
    UIImage *image = [UIImage imageNamed:[NSString stringWithFormat:@"pah%d",tagNum]];
    TouchImageView *touchImageView = [[TouchImageView alloc] initWithFrame:imageRect];
    imageCounter++;
    touchImageView.tag = imageCounter;
    touchImageView.image = image;
    touchImageView.center = CGPointMake(160.0, 230.0);
    [view addSubview:touchImageView];
}

undo{
       [[self.view viewWithTag:imageCounter] removeFromSuperview];
    imageCounter--;
}

UIImageView *imageView = touchImageView;

for(UIImageView *iV in view.subviews)
 {
    if(iV == imageView)
    {
       [iV removeFromSuperView];
    }
 }