swift Autolayout のサイズについて

swift
1import UIKit
2
3class ViewController: UIViewController {
4    var answer:Int?
5    var questionView = UITextView()
6    var buttonList:[UIButton] = []
7    
8    override func viewDidLoad() {
9        super.viewDidLoad()
10        // Do any additional setup after loading the view.
11        
12        answer = 0
13        questionView = setUpquestion(contents: "こんにちはわわわわわわ")
14        let c = setUpChoices(c1: "押してね！",c2: "押してね！!")
15        buttonList.append(c.0)
16        buttonList.append(c.1)
17    }
18    func setUpquestion(contents:String) -> UITextView{
19        let question = UITextView()
20        question.isEditable = false
21        question.translatesAutoresizingMaskIntoConstraints = false
22        question.isSelectable = false
23        question.font = UIFont.systemFont(ofSize: 23)
24        question.textColor = .lightGray
25        question.text = contents
26        question.sizeToFit()
27        question.center = self.view.center
28        self.view.addSubview(question)
29        
30        question.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive = true
31        question.centerYAnchor.constraint(equalTo: self.view.centerYAnchor).isActive = true
32        
33
34        return question
35    }
36    func modQuestion(view:UITextView,contents:String){
37        view.text = contents
38    }
39    func setUpChoices(c1:String,c2:String) -> (UIButton,UIButton){
40        let button1 = UIButton()
41        button1.setTitle(c1, for: .normal)
42        button1.sizeToFit()
43        button1.setTitleColor(.systemBlue, for: .normal)
44        button1.center = CGPoint(x: self.view.bounds.width / 4, y: self.view.bounds.height * 3 / 4)
45        button1.tag = 0
46        button1.addTarget(self, action: #selector(buttonAction(_:)), for: .touchUpInside)
47        self.view.addSubview(button1)
48        
49        let button2 = UIButton()
50        button2.setTitle(c2, for: .normal)
51        button2.sizeToFit()
52        button2.setTitleColor(.systemBlue, for: .normal)
53        button2.center = CGPoint(x: self.view.bounds.width * 3 / 4, y: self.view.bounds.height * 3 / 4)
54        button2.tag = 1
55        button2.addTarget(self, action: #selector(buttonAction(_:)), for: .touchUpInside)
56        self.view.addSubview(button2)
57        
58        return (button1,button2)
59    }
60    
61    func modButton(button:UIButton,str:String){
62        button.isEnabled = true
63        button.setTitle(str, for: .normal)
64        
65    }
66    
67    @objc func buttonAction(_ sender:UIButton){
68        if let ans = answer{
69            if sender.tag == ans{
70                print("正解")
71            }else{
72                print("不正解")
73            }
74        }
75        buttonList[0].isEnabled = false
76        buttonList[1].isEnabled = false
77        
78        DispatchQueue.main.asyncAfter(deadline: .now() + 3){
79            self.modQuestion(view: self.questionView, contents: "こんにちは")
80            self.modButton(button: self.buttonList[0], str: "Push1")
81            self.modButton(button: self.buttonList[1], str: "Push2")
82            
83            
84        }
85        
86    }
87    
88}
89

これの場合なぜ一番最初の"こんにちはわわわわわわ"のいちは真ん中にあるのに、後から変更した"こんにちは"では位置が真ん中に引き継がれないのでしょうか？これを解決するためにAutolayoutを設定しようと思ったんですけど、xとyは設定できたんですけど、sizeToFit()のように文字の大きなどによって変えることのできるAutolayoutはあるのでしょうか？question.widthAnchor.constraint(equalTo: 50)このような具体的な値などで設定するしかないのでしょうか？