Swift 带UIImageView的UIStackView不'；无法按预期处理约束

我有一个UIStackView（水平）将ArrangedSubView添加到UIStackView（垂直）中

水平视图有3个单元格：第一个是带有UILabel的addArrangedSubview，第二个是UIImageView（具有宽度和高度常量约束以保持我想要的大小）。第三个单元格是带有UILabel的addArrangedSubview。 我希望视图能适应整个屏幕的宽度

不幸的是，结果如下所示：

    let sv = UIStackView()
    sv.axis = .horizontal
    sv.alignment = .center
    sv.distribution = .fill
    sv.spacing = 10

    // Name
        var label = UILabel()
        label.numberOfLines = 0
        label.textAlignment = .natural
        label.text = poi.name
        label.font = UIFont.preferredFont(forTextStyle: .title1)
        sv.addArrangedSubview(label)

    // Open/closed
        let open = true
        let _ = addImageView(open ? #imageLiteral(resourceName: "Open") : #imageLiteral(resourceName: "Closed"), to: sv)

    // Stars
        let maxRank = 5
        let rank = 3
        label = UILabel()
        label.numberOfLines = 0
        label.textAlignment = .natural
        label.text = "".padding(right: rank, withPad: "★").padding(right: maxRank-rank, withPad: "☆")
        sv.addArrangedSubview(label)

    verticalStackView.addArrangedSubview(sv)

    let w: CGFloat = 32.0
    let r = CGRect(x: 0, y: 0, width: w, height: w)

    func addImageView(_ image: UIImage, to sv: UIStackView) {
        let iv = UIImageView()
        iv.contentMode = .scaleAspectFit
        iv.image = image

        //iv.translatesAutoresizingMaskIntoConstraints = true
        let constraints = [
            iv.widthAnchor .constraint(equalToConstant: w),
            iv.heightAnchor.constraint(equalToConstant: w)
        ]
        //let _ = constraints.map { $0.priority = .defaultHigh }
        NSLayoutConstraint.activate(constraints)
        /*
        iv.setContentCompressionResistancePriority(UILayoutPriority(rawValue: 1000.0), for: .horizontal)
        iv.setContentCompressionResistancePriority(UILayoutPriority(rawValue: 1000.0), for: .vertical)
        */
        if true {
            sv.addArrangedSubview(iv)
        } else {
            let v = UIView()
            v.layer.borderColor = UIColor.red.cgColor
            v.layer.borderWidth = 1
            v.addSubview(iv)
            sv.addArrangedSubview(v)
        }
    }

// Name
    var label = UILabel()
    label.numberOfLines = 0
    label.textAlignment = .natural
    label.text = poi.name
    label.font = UIFont.preferredFont(forTextStyle: .title1)
    label.setContentCompressionResistancePriority(UILayoutPriority.required, for: .horizontal)

    sv.addArrangedSubview(label)

// Open/closed
    let open = true
    let _ = addImageView(open ? #imageLiteral(resourceName: "Open") : #imageLiteral(resourceName: "Closed"), to: sv)

// Stars
    let maxRank = 5
    let rank = 3
    label = UILabel()
    label.numberOfLines = 0
    label.textAlignment = .natural
    label.text = "".padding(right: rank, withPad: "★").padding(right: maxRank-rank, withPad: "☆")
    label.setContentCompressionResistancePriority(UILayoutPriority.required, for: .horizontal)

    sv.addArrangedSubview(label)

verticalStackView.addArrangedSubview(sv)

我的代码如下：

    let sv = UIStackView()
    sv.axis = .horizontal
    sv.alignment = .center
    sv.distribution = .fill
    sv.spacing = 10

    // Name
        var label = UILabel()
        label.numberOfLines = 0
        label.textAlignment = .natural
        label.text = poi.name
        label.font = UIFont.preferredFont(forTextStyle: .title1)
        sv.addArrangedSubview(label)

    // Open/closed
        let open = true
        let _ = addImageView(open ? #imageLiteral(resourceName: "Open") : #imageLiteral(resourceName: "Closed"), to: sv)

    // Stars
        let maxRank = 5
        let rank = 3
        label = UILabel()
        label.numberOfLines = 0
        label.textAlignment = .natural
        label.text = "".padding(right: rank, withPad: "★").padding(right: maxRank-rank, withPad: "☆")
        sv.addArrangedSubview(label)

    verticalStackView.addArrangedSubview(sv)

    let w: CGFloat = 32.0
    let r = CGRect(x: 0, y: 0, width: w, height: w)

    func addImageView(_ image: UIImage, to sv: UIStackView) {
        let iv = UIImageView()
        iv.contentMode = .scaleAspectFit
        iv.image = image

        //iv.translatesAutoresizingMaskIntoConstraints = true
        let constraints = [
            iv.widthAnchor .constraint(equalToConstant: w),
            iv.heightAnchor.constraint(equalToConstant: w)
        ]
        //let _ = constraints.map { $0.priority = .defaultHigh }
        NSLayoutConstraint.activate(constraints)
        /*
        iv.setContentCompressionResistancePriority(UILayoutPriority(rawValue: 1000.0), for: .horizontal)
        iv.setContentCompressionResistancePriority(UILayoutPriority(rawValue: 1000.0), for: .vertical)
        */
        if true {
            sv.addArrangedSubview(iv)
        } else {
            let v = UIView()
            v.layer.borderColor = UIColor.red.cgColor
            v.layer.borderWidth = 1
            v.addSubview(iv)
            sv.addArrangedSubview(v)
        }
    }

// Name
    var label = UILabel()
    label.numberOfLines = 0
    label.textAlignment = .natural
    label.text = poi.name
    label.font = UIFont.preferredFont(forTextStyle: .title1)
    label.setContentCompressionResistancePriority(UILayoutPriority.required, for: .horizontal)

    sv.addArrangedSubview(label)

// Open/closed
    let open = true
    let _ = addImageView(open ? #imageLiteral(resourceName: "Open") : #imageLiteral(resourceName: "Closed"), to: sv)

// Stars
    let maxRank = 5
    let rank = 3
    label = UILabel()
    label.numberOfLines = 0
    label.textAlignment = .natural
    label.text = "".padding(right: rank, withPad: "★").padding(right: maxRank-rank, withPad: "☆")
    label.setContentCompressionResistancePriority(UILayoutPriority.required, for: .horizontal)

    sv.addArrangedSubview(label)

verticalStackView.addArrangedSubview(sv)

我的工具功能如下：

    let sv = UIStackView()
    sv.axis = .horizontal
    sv.alignment = .center
    sv.distribution = .fill
    sv.spacing = 10

    // Name
        var label = UILabel()
        label.numberOfLines = 0
        label.textAlignment = .natural
        label.text = poi.name
        label.font = UIFont.preferredFont(forTextStyle: .title1)
        sv.addArrangedSubview(label)

    // Open/closed
        let open = true
        let _ = addImageView(open ? #imageLiteral(resourceName: "Open") : #imageLiteral(resourceName: "Closed"), to: sv)

    // Stars
        let maxRank = 5
        let rank = 3
        label = UILabel()
        label.numberOfLines = 0
        label.textAlignment = .natural
        label.text = "".padding(right: rank, withPad: "★").padding(right: maxRank-rank, withPad: "☆")
        sv.addArrangedSubview(label)

    verticalStackView.addArrangedSubview(sv)

    let w: CGFloat = 32.0
    let r = CGRect(x: 0, y: 0, width: w, height: w)

    func addImageView(_ image: UIImage, to sv: UIStackView) {
        let iv = UIImageView()
        iv.contentMode = .scaleAspectFit
        iv.image = image

        //iv.translatesAutoresizingMaskIntoConstraints = true
        let constraints = [
            iv.widthAnchor .constraint(equalToConstant: w),
            iv.heightAnchor.constraint(equalToConstant: w)
        ]
        //let _ = constraints.map { $0.priority = .defaultHigh }
        NSLayoutConstraint.activate(constraints)
        /*
        iv.setContentCompressionResistancePriority(UILayoutPriority(rawValue: 1000.0), for: .horizontal)
        iv.setContentCompressionResistancePriority(UILayoutPriority(rawValue: 1000.0), for: .vertical)
        */
        if true {
            sv.addArrangedSubview(iv)
        } else {
            let v = UIView()
            v.layer.borderColor = UIColor.red.cgColor
            v.layer.borderWidth = 1
            v.addSubview(iv)
            sv.addArrangedSubview(v)
        }
    }

// Name
    var label = UILabel()
    label.numberOfLines = 0
    label.textAlignment = .natural
    label.text = poi.name
    label.font = UIFont.preferredFont(forTextStyle: .title1)
    label.setContentCompressionResistancePriority(UILayoutPriority.required, for: .horizontal)

    sv.addArrangedSubview(label)

// Open/closed
    let open = true
    let _ = addImageView(open ? #imageLiteral(resourceName: "Open") : #imageLiteral(resourceName: "Closed"), to: sv)

// Stars
    let maxRank = 5
    let rank = 3
    label = UILabel()
    label.numberOfLines = 0
    label.textAlignment = .natural
    label.text = "".padding(right: rank, withPad: "★").padding(right: maxRank-rank, withPad: "☆")
    label.setContentCompressionResistancePriority(UILayoutPriority.required, for: .horizontal)

    sv.addArrangedSubview(label)

verticalStackView.addArrangedSubview(sv)

注1：我做了一些实验，因此得到了注释代码

注2：屏幕截图上的红色条是我的手绘，以便于理解细胞的布局

[更新]

为了澄清问题，我在UIImageView中添加了一个约束，但没有任何约束，一切都正常。我添加约束的原因是为了保持UIImageView的平方和正确的尺寸。 出于这个原因，我添加了一个UIView作为中间元素，以吸收UIStackView约束设置到内部元素的强度（因此if-false代码）。但是我需要在UIView中添加额外的约束以使UIImageView居中，这听起来有点过度使用布局系统。当然 我可能错过了一些可以简化整个过程的东西。

你能帮我吗 -尝试为根StackView添加约束，尾部、顶部、底部和前导等于常量0。 -尝试使用.fill而不是.center更改根堆栈视图的对齐方式

• 如果要使标签更灵活，请使用比其他属性（251250750）小得多的值（通常为248748）来设置压缩阻力和上下文拥抱属性

谢谢，

---

J

我终于解决了这个问题：我将电阻压缩优先级更改为。标签和UIImageView需要：

label.setContentCompressionResistancePriority(UILayoutPriority.required, for: .horizontal)

现在，相同的代码如下所示：

    let sv = UIStackView()
    sv.axis = .horizontal
    sv.alignment = .center
    sv.distribution = .fill
    sv.spacing = 10

    // Name
        var label = UILabel()
        label.numberOfLines = 0
        label.textAlignment = .natural
        label.text = poi.name
        label.font = UIFont.preferredFont(forTextStyle: .title1)
        sv.addArrangedSubview(label)

    // Open/closed
        let open = true
        let _ = addImageView(open ? #imageLiteral(resourceName: "Open") : #imageLiteral(resourceName: "Closed"), to: sv)

    // Stars
        let maxRank = 5
        let rank = 3
        label = UILabel()
        label.numberOfLines = 0
        label.textAlignment = .natural
        label.text = "".padding(right: rank, withPad: "★").padding(right: maxRank-rank, withPad: "☆")
        sv.addArrangedSubview(label)

    verticalStackView.addArrangedSubview(sv)

    let w: CGFloat = 32.0
    let r = CGRect(x: 0, y: 0, width: w, height: w)

    func addImageView(_ image: UIImage, to sv: UIStackView) {
        let iv = UIImageView()
        iv.contentMode = .scaleAspectFit
        iv.image = image

        //iv.translatesAutoresizingMaskIntoConstraints = true
        let constraints = [
            iv.widthAnchor .constraint(equalToConstant: w),
            iv.heightAnchor.constraint(equalToConstant: w)
        ]
        //let _ = constraints.map { $0.priority = .defaultHigh }
        NSLayoutConstraint.activate(constraints)
        /*
        iv.setContentCompressionResistancePriority(UILayoutPriority(rawValue: 1000.0), for: .horizontal)
        iv.setContentCompressionResistancePriority(UILayoutPriority(rawValue: 1000.0), for: .vertical)
        */
        if true {
            sv.addArrangedSubview(iv)
        } else {
            let v = UIView()
            v.layer.borderColor = UIColor.red.cgColor
            v.layer.borderWidth = 1
            v.addSubview(iv)
            sv.addArrangedSubview(v)
        }
    }

// Name
    var label = UILabel()
    label.numberOfLines = 0
    label.textAlignment = .natural
    label.text = poi.name
    label.font = UIFont.preferredFont(forTextStyle: .title1)
    label.setContentCompressionResistancePriority(UILayoutPriority.required, for: .horizontal)

    sv.addArrangedSubview(label)

// Open/closed
    let open = true
    let _ = addImageView(open ? #imageLiteral(resourceName: "Open") : #imageLiteral(resourceName: "Closed"), to: sv)

// Stars
    let maxRank = 5
    let rank = 3
    label = UILabel()
    label.numberOfLines = 0
    label.textAlignment = .natural
    label.text = "".padding(right: rank, withPad: "★").padding(right: maxRank-rank, withPad: "☆")
    label.setContentCompressionResistancePriority(UILayoutPriority.required, for: .horizontal)

    sv.addArrangedSubview(label)

verticalStackView.addArrangedSubview(sv)

以及：