Estimated height for a cell based on string value and font type

EstimateCellHeight.swift

func estimateHeight(string: String?, font: UIFont, right: CGFloat = 0, left: CGFloat = 0) -> CGFloat {
    guard let string = string else { return 0 }
    let width = view.frame.width - right - left
    let rect = NSString(string: string).boundingRect(with: CGSize(width: width, height: 1000.0), options: NSStringDrawingOptions.usesFontLeading.union(NSStringDrawingOptions.usesLineFragmentOrigin), attributes: [NSAttributedStringKey.font: font], context: nil)
    return rect.height
}

// Usage for UICollectionViewCell

override func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
  let margin = 16
  let cellHeight = estimateHeight(string: "Long string here!", font: UIFont(name: UIFont.preferredFont(forTextStyle: .body), right: margin, left: margin)
  return CGSize(width: view.frame.width, height: margin + cellHeight + margin)
}