Set collectionView size. (sizeForItemAtIndexPath function is not working) Swift 3

Question

I have a tableView and in every tableViewCell is a collectionView.

I am trying to change the collectionView size with this code:

 func collectionView(_ collectionView: UICollectionView,                     layout collectionViewLayout: UICollectionViewLayout,                     sizeForItemAt indexPath: IndexPath) -> CGSize {      if collectionView.tag == 2{          return CGSize(width: 100, height: 100)      }else if collectionView.tag == 4 {           return CGSize(width: 222, height: 200)      }else{           return CGSize(width: 10, height: 10)     }  } 

The problem is that there is no error but cells do not change sizes

If you need to know something more, just write a comment.

Thank you.

Answer 1

First, don't forget to extends from UICollectionViewDelegateFlowLayout delegate.

For single collectionview display logic :

 func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {     let width = ((collectionView.frame.width - 15) / 2) // 15 because of paddings     print("cell width : \(width)")     return CGSize(width: width, height: 200) } 

And important point in storyboard don't forget Estimate Size : None