send to instance already dealloc nil error

这个是因为发送消息的对象已经被dealloc了，然后再次发送[release]请求就不行了。所以可以retain或者alloc对象

if (self.buttonsList) {
        
        for (int index = 0; index < 9; index ++) {
            
            UIButton *button = [[UIButton alloc]init];
            button.backgroundColor = [UIColor blueColor];
            button.tag = index;
            if (cellOffsetx >= (self.bgscrollview.frame.size.width - 5.0f)) {
                
                //new line
                ++scrollviewLineNumber;
                cellOffsetx = 5.0f;
            }
            
            button.frame = CGRectMake(cellOffsetx, cellHeight*scrollviewLineNumber + cellOffsety*scrollviewLineNumber + cellOffsety,cellWidth, cellHeight);
            cellOffsetx = cellOffsetx + cellWidth + 5.0f;
            
            //store the button
            [self.buttonsList addObject:button];
            //[self.bgscrollview addSubview:[self.buttonsList objectAtIndex:index]];
            [button release];

}
      
    }

- (void)dealloc
{
 
    self.bgscrollview.delegate = nil;
    [_buttonsList release];  ／／不使用alloc的话会crash
    _buttonsList = nil;
    [_entriesArray release];
    _entriesArray = nil;
    [_alertView release];
    _alertView = nil;
    [_albumTitle release];
    _albumTitle = nil;
    [_bgscrollview release];
    _bgscrollview = nil;
    [_photosList release];
    _photosList = nil;
    [_customNav release];
    _customNav = nil;
    [_localView release];
    _localView = nil;
    [super dealloc];
}