UICollectionView insert cells above maintaining position (like Messages.app)

Question

By default Collection View maintains content offset while inserting cells. On the other hand I\'d like to insert cells above the currently displaying ones so that they appea

Answer 1

// stop scrolling
setContentOffset(contentOffset, animated: false)

// calculate the offset and reloadData
let beforeContentSize = contentSize
reloadData()
layoutIfNeeded()
let afterContentSize = contentSize

// reset the contentOffset after data is updated
let newOffset = CGPoint(
  x: contentOffset.x + (afterContentSize.width - beforeContentSize.width),
  y: contentOffset.y + (afterContentSize.height - beforeContentSize.height))
setContentOffset(newOffset, animated: false)