Swift无Storyboard下UIView放入UIScrollView的显示问题排查

以下是针对你的MVC结构代码的具体修改方案，按优先级排查调整：

1. 配置正确的Auto Layout约束（核心解决点） #

UIScrollView的子视图必须明确设置尺寸约束，或通过内部控件撑出明确大小，同时要绑定与scrollView的四边对齐约束，否则子视图会因尺寸为0而无法显示。

修改CalcTypeViewController的UI配置代码： #

class CalcTypeViewController: UIViewController {
    private let scrollView = UIScrollView()
    private let calcTypeView = CalcTypeView()

    override func viewDidLoad() {
        super.viewDidLoad()
        setupUI()
    }

    private func setupUI() {
        // 配置scrollView铺满控制器视图
        view.addSubview(scrollView)
        scrollView.translatesAutoresizingMaskIntoConstraints = false
        scrollView.backgroundColor = .gray
        
        NSLayoutConstraint.activate([
            scrollView.topAnchor.constraint(equalTo: view.topAnchor),
            scrollView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            scrollView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor)
        ])

        // 添加并配置calcTypeView
        scrollView.addSubview(calcTypeView)
        calcTypeView.translatesAutoresizingMaskIntoConstraints = false
        calcTypeView.backgroundColor = .red

        // 关键约束：绑定四边+强制宽度与scrollView一致，避免子视图宽度为0
        NSLayoutConstraint.activate([
            calcTypeView.topAnchor.constraint(equalTo: scrollView.topAnchor),
            calcTypeView.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor),
            calcTypeView.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor),
            calcTypeView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor),
            calcTypeView.widthAnchor.constraint(equalTo: scrollView.widthAnchor)
        ])

        // 若calcTypeView内部无足够控件撑高，需手动设置高度约束
        // calcTypeView.heightAnchor.constraint(equalToConstant: 800).isActive = true
    }
}

2. 确保自定义CalcTypeView内部布局有效 #

如果CalcTypeView是自定义视图，需保证其内部子控件的约束能撑出视图的明确高度，否则视图会因高度为0而不可见：

class CalcTypeView: UIView {
    override init(frame: CGRect) {
        super.init(frame: frame)
        setupInternalViews()
    }

    required init?(coder: NSCoder) {
        super.init(coder: coder)
        setupInternalViews()
    }

    private func setupInternalViews() {
        // 添加示例控件撑高视图
        let testLabel = UILabel()
        testLabel.text = "CalcTypeView内容"
        testLabel.font = .systemFont(ofSize: 24)
        testLabel.translatesAutoresizingMaskIntoConstraints = false
        addSubview(testLabel)

        NSLayoutConstraint.activate([
            testLabel.topAnchor.constraint(equalTo: topAnchor, constant: 20),
            testLabel.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 20),
            testLabel.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -20),
            testLabel.bottomAnchor.constraint(equalTo: bottomAnchor, constant: -20)
        ])
    }
}

3. 必做：禁用自动调整掩码 #

确保所有通过代码添加的视图都设置了translatesAutoresizingMaskIntoConstraints = false，否则手动配置的约束会被系统自动生成的约束覆盖，导致布局失效。

4. 备选方案：手动设置contentSize（非推荐） #

若不想使用Auto Layout，可在viewDidLayoutSubviews中手动指定scrollView的内容尺寸：

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()
    scrollView.contentSize = calcTypeView.bounds.size
}

内容的提问来源于stack exchange，提问作者Hoyeon Lee