Resize the cell of UICollectionView without the reload methods

I got the solution to my question with following line of code.

collectionView?.collectionViewLayout.invalidateLayout()

N.B. To animate this resizing, use UIView.animate :

let duration: TimeInterval = 0.3
UIView.animate(withDuration: duration, animations: {
    collectionView.collectionViewLayout.invalidateLayout() 
})

I can confirm that Payal Maniyar's solution also works for UICollectionCompositional layouts as well. In my situation, I had a CollectionViewCell which only embedded a UITextView. Compositional layout correctly figured out the initial size of the text view in the cell. (Side note: you do this by disabling scrolling within the UITextView since it is already inside of another scrollable view). The problem was as the user typed directly into the text view, I wanted to change the height of the cell without reloading it. I wanted to avoid reloading the cell for 2 reasons. a) the reloaded cell flickers as the user types, b) the text view loses focus; thereby, forcing the user to click on the text view again to continue to type. So my solution is as follows:

1. I have a cell with only UITextView inside of it where the cell is also the UITextView's delegate as such:

   class MyCollectionCell: UICollectionViewCell {
     @IBOutlet private weak var myTextView: UITextView!
     //this local variable used to determine if the intrinsic content size has changed or not
     private var textViewHeight: CGFloat = .zero
     ...
     ...
     override func awakeFromNib() {
      super.awakeFromNib()
      myTextView.delegate = self
     }
     ...
     ...
   }
   

2. Conform this cell to UITextViewDelegate

   extension MyCollectionCell: UITextViewDelegate { 
   
   func textViewShouldBeginEditing(_ textView: UITextView) -> Bool {
     //this assumes that collection view already correctly laid out the cell
     //to the correct height for the contents of the UITextView
     //textViewHeight simply needs to catch up to it before user starts typing
     let fittingSize = textView.sizeThatFits(CGSize(width: myTextView.frame.width, height: CGFloat.greatestFiniteMagnitude))
     textViewHeight = fittingSize.height
   
     return true
   }
   
   func textViewDidChange(_ textView: UITextView) {
     //flag to determine whether textview's size is changing
     var shouldResize = false
     //calculate fitting size after the content has changed
     let fittingSize = textView.sizeThatFits(CGSize(width: myTextView.frame.width, height: CGFloat.greatestFiniteMagnitude))
   
     //if the current height is not equal to 
     if textViewHeight != fittingSize.height {
       shouldResize = true
       //save the new height 
       textViewHeight = fittingSize.height
     }
   
     //notify the cell's delegate (most likely a UIViewController) 
     //that UITextView's intrinsic content size has changed
     //perhaps with a protocol such as this:
     delegate?.textViewDidChange(newText: textView.text, alsoRequiresResize: shouldResize)
   }
   

3. Then when the delegate receives the notification, perhaps saves the updated text and updates the layout such as this:

   myCollectionView.collectionViewLayout.invalidateLayout()
   

The best part of this solution is that you do not have to invoke collectionView(_:layout:sizeForItemAt:) to resize the cell because you are not using the clunky FlowLayout to begin with.

Cheers!