When text is too small to fit in UITextView

ExpandUITextView.swift

extension UITextView {

  func sizeThatWillFitAllText()->CGFloat {
    return self.sizeThatFits((self.frame.size)).height
  }
}

self.textViewHeightConstraintOutlet.constant = desiredTextViewHeight < CGFloat(75) ? desiredTextViewHeight : CGFloat(75)
      
      let textViewWantsHeightObservable = self.textViewHeightConstraintOutlet
        .rx.observe(CGFloat.self, "constant")
        .flatMapLatest({ [weak self] height -> Observable<CGFloat> in
          guard let _ = self else { return Observable.empty() }
          return Observable.of(desiredTextViewHeight)
        })
      
      textViewWantsHeightObservable
        .do(onNext: { height in print(height) })
        .flatMapLatest({ height in
          return Observable.of(height < CGFloat(75))
        })
        .asDriver(onErrorJustReturn: false)
        .drive(readMoreLabelOutlet.rx_hidden)
        .addDisposableTo(disposeBag)
      let readMoreDescriptionGestureRecognizer = UITapGestureRecognizer(target: self, action: nil)
      readMoreLabelOutlet.addGestureRecognizer(readMoreDescriptionGestureRecognizer)

      readMoreDescriptionGestureRecognizer.rx.event
        .single()
        .flatMapLatest({ _ in
          return textViewWantsHeightObservable
        })
        .single()
        .subscribe (onNext : { [weak self] height in
          guard let _ = self else { return }
          self!.textViewHeightConstraintOutlet.constant = height
          self!.readMoreLabelOutlet.isHidden = true
          self!.tableView?.beginUpdates()
          self!.tableView?.endUpdates()
        })
        .addDisposableTo(rx_disposeBag)

// just a snippet to remember the sizeThatFits bit
// self.textViewHeightConstraintOutlet
//   .rx.observe(CGFloat.self, "constant")
//   .subscribe(onNext:  { [weak self] constant in
//     let isTextLargerThanView = (self?.descriptionOutlet.sizeThatFits((self?.descriptionOutlet.frame.size)!).height)! > CGFloat(50)

//     self?.moreLabelOutlet.text = constant == 50 ? "more >" : "< less"
//     self?.moreLabelOutlet.underLine()
//     self?.moreLabelOutlet.isHidden = isTextLargerThanView ? false : true
//     detailsGestureRecognizer.isEnabled = isTextLargerThanView ? true : false
//     moreGestureRecognizer.isEnabled = isTextLargerThanView ? true : false
//   })
//   .addDisposableTo(rx_disposeBag)