具有垂直堆栈视图的 UIScrollView 水平滚动但不是垂直滚动

Question

我遵循了类似 answer and while it scrolled vertically for them it does not for me. The label in the code is just a test there are far more in the actual program but they are added from firebase later on so I'm not sure if that changes anything. While it's not super important I would prefer to figure this out programmatically as I am more capable in that area. I'm not great at asking questions or providing the right code so the whole project is here

的确切代码

`

@IBOutlet weak var history: UIStackView!
@IBOutlet weak var scrollView: UIScrollView!

var ref: DatabaseReference!


override func viewDidLoad() {
    super.viewDidLoad()
    view.addSubview(scrollView)

    ref = Database.database().reference()
    
    let label = UILabel(frame: CGRect.init())
    label.text = "Label"
    history.addArrangedSubview(label)
    
    scrollView.contentSize = CGSize(width: view.bounds.width, height: view.bounds.height)

    history.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor).isActive = true
    history.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor).isActive = true
    history.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor).isActive = true
    history.topAnchor.constraint(equalTo: scrollView.topAnchor).isActive = true
    history.widthAnchor.constraint(equalTo: scrollView.widthAnchor).isActive = true
    //history.heightAnchor.constraint(lessThanOrEqualTo: scrollView.heightAnchor).isActive = true

    scrollView.addSubview(history)
    view.addSubview(scrollView)
    `

Answer 1

你做错了很多事...

您的代码为 history 堆栈视图和 scrollView 显示了 @IBOutlet，这意味着您已将它们添加到 Storyboard 中？如果是这样，你应该而不是做：

scrollView.addSubview(history)
view.addSubview(scrollView)

因为它们在添加到 Storyboard 时已经存在。此外，人们会希望您在 Storyboard 中添加约束。

但是，如果您想通过代码完成所有操作，请使用这个非常简单示例：

class ViewController: UIViewController {

    var history: UIStackView!
    var scrollView: UIScrollView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        history = UIStackView()
        // vertical stack
        history.axis = .vertical
        // arranged subviews fill the width
        history.alignment = .fill
        // distribution
        history.distribution = .fill
        // spacing
        history.spacing = 12
        
        scrollView = UIScrollView()
        // so we can see it
        scrollView.backgroundColor = .cyan
        
        // we're using auto-layout constraints
        scrollView.translatesAutoresizingMaskIntoConstraints = false
        history.translatesAutoresizingMaskIntoConstraints = false

        // add the stack view to the scroll view
        scrollView.addSubview(history)
        
        // add the scroll view to the view
        view.addSubview(scrollView)

        // no no no... let auto-layout handle it
        //scrollView.contentSize = CGSize(width: view.bounds.width, height: view.bounds.height)
        
        // respect safe area
        let g = view.safeAreaLayoutGuide
        
        NSLayoutConstraint.activate([
            
            // constrain scroll view with 20-pts on each side
            scrollView.topAnchor.constraint(equalTo: g.topAnchor, constant: 20.0),
            scrollView.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
            scrollView.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
            scrollView.bottomAnchor.constraint(equalTo: g.bottomAnchor, constant: -20.0),

            // constrain stack view to all 4 sides of scroll view with 8-pts on each side
            history.topAnchor.constraint(equalTo: scrollView.topAnchor, constant: 8.0),
            history.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor, constant: 8.0),
            history.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor, constant: -8.0),
            history.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor, constant: -8.0),
            
            // constrain stack view width to scroll view width minus 16 (for 8-pts on each side)
            history.widthAnchor.constraint(equalTo: scrollView.widthAnchor, constant: -16),

        ])

        // let's add 30 labels to the stack view
        for i in 1...30 {
            let label = UILabel()
            label.text = "Label: \(i)"
            // so we can see the label frames
            label.backgroundColor = .yellow
            history.addArrangedSubview(label)
        }

    }
    
}

附带说明：阅读文档并完成几个滚动视图教程将使您受益匪浅。看起来你试图使用你链接到的问题中的片段，但不知道它是什么意思。

具有垂直堆栈视图的 UIScrollView 水平滚动但不是垂直滚动

UIScrollView with vertical stackview scrolls horizontally but not vertically

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