title: iOS: UICollectionViewCell animation change cells content partially
body: <p>I have UICollectionView with cells. I need to change cell image in UIImageView. But I need to change it not in one cell, but from one cell to 30, for example. (Cells that need to change value is changes.) 
  I want to make this with animation. Also, I don't want to simultaneous change all cell that must be changed. I want firs change some of it, after a short amount of time change more and so on until all will be changed. Is it possible? And is the any example of how I can do this?</p>
  
  <p>I already made a method that change all at once, but this not what I want. If somebody want to look at this code, I'll post it here after update, for now I don't see a reason to post it (because I think this a different ways at all, to show simultaneous change and partial changes).</p>