class RotateTextViewVC: UIViewController {
	
	let tv = UITextView()
	
	override func viewDidLoad() {
		super.viewDidLoad()
		view.backgroundColor = .systemYellow

		tv.isScrollEnabled = false
		tv.text = "This is some sample text for the text view."
		tv.font = .systemFont(ofSize: 24.0, weight: .regular)

		// add a slider to rotate the text view
		let slider = UISlider()
		slider.addTarget(self, action: #selector(sliderChanged(_:)), for: .valueChanged)
		
		slider.translatesAutoresizingMaskIntoConstraints = false
		view.addSubview(slider)
		
		tv.translatesAutoresizingMaskIntoConstraints = false
		view.addSubview(tv)
		
		let g = view.safeAreaLayoutGuide
		NSLayoutConstraint.activate([
			slider.topAnchor.constraint(equalTo: g.topAnchor, constant: 40.0),
			slider.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
			slider.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),

			tv.centerXAnchor.constraint(equalTo: view.centerXAnchor),
			tv.centerYAnchor.constraint(equalTo: view.centerYAnchor),
			tv.widthAnchor.constraint(equalToConstant: 200.0),
		])
		
		slider.value = 0.5
	}
	@objc func sliderChanged(_ sender: UISlider) {

		let deg: CGFloat = (CGFloat(sender.value) - 0.5) * 720.0
		let radians = deg * .pi / 180.0
		tv.layer.transform = CATransform3DRotate(CATransform3DIdentity, radians, 0, 0, 1)

	}
	
}