Elrond

@zjfjack I also have the top or bottom with some residual UI. sometimes i can't call [func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) ] and can't scroll horizontal or vertical...

sometimes i scroll to the top or bottom with some residual UI:   

sometimes i scroll to the top or bottom, then i can't call [func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) ] when tap the cell, and also can't scroll opposite horizontal...

我们这里也出现过同样的问题，使用的是YYWebImage 1.0.3，图片服务器是阿里云，出现概率挺小的，但是也陆陆续续出现过几次，就是图片地址缓存成其它图片了（比如有A和B地址，A和B地址在我们的应用里错误的显示了同一张图片，但是阿里云存的不是同一张），清空缓存，又可以正常工作了。