NSTextView/UITextView subclass with an expandable See More link

import SeeMoreTextView
...
var seeMoreTextView: SeeMoreTextView!
var scrollViewHeightConstraint: NSLayoutConstraint!

override func viewWillAppear() {
    super.viewWillAppear()

    seeMoreTextView = SeeMoreTextView(frame: .zero)
    seeMoreTextView.translatesAutoresizingMaskIntoConstraints = false
    
    let scrollView = CustomScrollView()
    view.addSubview(scrollView)
    scrollView.translatesAutoresizingMaskIntoConstraints = false
    scrollView.borderType = .noBorder
    scrollView.hasVerticalScroller = true
    scrollView.hasHorizontalScroller = false
    scrollView.documentView = seeMoreTextView
    
    scrollViewHeightConstraint = scrollView.heightAnchor.constraint(equalToConstant: 0)
    // See more text view's height change hook, which can be used for custom layout handling
    seeMoreTextView.onHeightChange = { sender in
        self.scrollViewHeightConstraint.constant = min(sender.height, 100)
        (sender.enclosingScrollView as! CustomScrollView).isEnabled = sender.isExpanded
    }
    
    NSLayoutConstraint.activate([
        scrollView.centerXAnchor.constraint(equalTo: view.centerXAnchor),
        scrollView.topAnchor.constraint(equalTo: view.topAnchor, constant: 10),
        scrollViewHeightConstraint,
        scrollView.widthAnchor.constraint(equalTo: seeMoreTextView.widthAnchor),
        scrollView.widthAnchor.constraint(equalToConstant: 400),
    ])

    // Full text to display
    let str = "On the other hand, ...."
    seeMoreTextView.contents = NSAttributedString(string: str, attributes: [
            .font: NSFontManager.shared.font(withFamily: "Helvetica", traits: [], weight: 5, size: 14)!
        ])
    // Number of lines to display in collapsed state
    seeMoreTextView.collapsedLineCount = 2
}

// NSScrollView subclass disabling scrolling on demand
class CustomScrollView: NSScrollView {
    var isEnabled = false
    override func scrollWheel(with event: NSEvent) {
        if isEnabled {
            super.scrollWheel(with: event)
        } else {
            nextResponder?.scrollWheel(with: event)
        }
    }
}

platform :osx, '10.12'

target 'YOUR-TARGET' do
  use_frameworks!
  pod 'SeeMoreTextView', :git => 'https://github.com/SergeBouts/SeeMoreTextView.git'
end