Nivo滑块不居中(Nivo Slider is not centered)

 只是猜测：在插入第一张图像时，收藏视图可能尚未加载其数据。 但是，在异常消息中，集合视图声明“知道”插入之前的项目数量（1）。 因此，它可能在insertItemsAtIndexPaths:延迟加载其数据insertItemsAtIndexPaths:并将结果作为“之前”状态。 此外，插入后无需重新加载数据。 
 
 长话短说，移动了 
 
[cv reloadData];
 
 得到 
 
if ([imageViews count] == 0)  {
    [self.noImagesLabel removeFromSuperview];
    [self.imageDisplayCell.contentView addSubview:cv];
    [cv reloadData];
}

Just a guess: at the time you are inserting the first image, the collection view may not yet have loaded its data. However, in the exception message, the collection view claims to "know" the number of items before the insertion (1). Therefore, it could have lazily loaded its data in insertItemsAtIndexPaths: and taken the result as "before" state. Also, you don't need to reload data after an insertion.
 
Long story short, move the
 
[cv reloadData];
 
up to get
 
if ([imageViews count] == 0)  {
    [self.noImagesLabel removeFromSuperview];
    [self.imageDisplayCell.contentView addSubview:cv];
    [cv reloadData];
}