如何将textview文本高度限制为10行，然后在Swift3中滚动其余文本

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        
        let textView = UITextView(frame: CGRect(x: 0, y: 0, width: 200, height: 0))
        textView.translatesAutoresizingMaskIntoConstraints = false
        textView.isScrollEnabled = true
        textView.textContainer.maximumNumberOfLines = 10
        textView.textContainer.lineBreakMode = .byTruncatingTail
        
        view.addSubview(textView)
        
        // 添加约束
        textView.topAnchor.constraint(equalTo: view.topAnchor, constant: 20).isActive = true
        textView.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 20).isActive = true
        textView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -20).isActive = true
        textView.heightAnchor.constraint(equalToConstant: textView.contentSize.height).isActive = true
        
        // 设置文本
        textView.text = "这是一段超过10行的文本，当超过10行时，TextView将会滚动其余文本。"
    }
}