当帧小于要求时,为UIStackView中的第一个UILabel赋予更高的优先级

这应该做到:

    var p: Float = 1000
    for v in stackView.arrangedSubviews {
        v.setContentCompressionResistancePriority(UILayoutPriority(rawValue: p), for: .vertical)
        p -= 1
    }
    

不过,使用堆栈视图有点奇怪,它可能最终不能满足您的需要。

例如,使用 100 x 150 框架和14个标签,我们得到:

正如我们所见,底部的标签有点“关闭”

而且,只有5个标签,我们得到:

顶部标签的高度会被拉长,除非我们用内容优先权做同样的事情。。。在这种情况下,底部标签会被拉伸。

更好的方法是将堆栈视图嵌入 UIView UIView公司 .clipsToBounds = true

有14个标签:

下面是要玩的代码。。。

方法1:

class FrankMethod1ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        
        let stackView = UIStackView()
        stackView.alignment = .leading
        stackView.axis = .vertical
        
        view.addSubview(stackView)
        stackView.frame = CGRect(x: 100, y: 100, width: 100, height: 150)
        
        // change to (0..<5) to see the stretching
        (0..<15).forEach {
            let label = UILabel()
            label.text = "text \($0)"
            label.backgroundColor = .red
            stackView.addArrangedSubview(label)
        }

        var p: Float = 1000
        for v in stackView.arrangedSubviews {
            v.setContentCompressionResistancePriority(UILayoutPriority(rawValue: p), for: .vertical)
            p -= 1
        }

    }

}

class FrankMethod2ViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let cView = UIView()
        cView.frame = CGRect(x: 100, y: 100, width: 100, height: 150)
        cView.clipsToBounds = true
        
        // so we can see the view frame
        cView.backgroundColor = .cyan
        
        view.addSubview(cView)
        
        let stackView = UIStackView()
        stackView.alignment = .leading
        stackView.axis = .vertical
        
        cView.addSubview(stackView)
        
        stackView.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            stackView.topAnchor.constraint(equalTo: cView.topAnchor),
            stackView.leadingAnchor.constraint(equalTo: cView.leadingAnchor),
            stackView.trailingAnchor.constraint(equalTo: cView.trailingAnchor),
        ])
        
        // change to (0..<5) to see NO stretching
        (0..<15).forEach {
            let label = UILabel()
            label.text = "text \($0)"
            label.backgroundColor = .red
            stackView.addArrangedSubview(label)
        }
        
    }
    
}

编辑

我得到的是:

import UIKit
import PlaygroundSupport

class PlaygroundFrankViewController: UIViewController {

    override func loadView() {
        let view = UIView()
        view.backgroundColor = .white
        self.view = view
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let stackView1 = UIStackView()
        stackView1.alignment = .leading
        stackView1.axis = .vertical
        
        view.addSubview(stackView1)
        stackView1.frame = CGRect(x: 50, y: 50, width: 100, height: 150)
        
        // change to (0..<5) to see the stretching
        (0..<15).forEach {
            let label = UILabel()
            label.text = "text \($0)"
            label.backgroundColor = .red
            stackView1.addArrangedSubview(label)
        }
        
        var p: Float = 1000
        for v in stackView1.arrangedSubviews {
            v.setContentCompressionResistancePriority(UILayoutPriority(rawValue: p), for: .vertical)
            p -= 1
        }

        let stackView2 = UIStackView()
        stackView2.alignment = .leading
        stackView2.axis = .vertical
        
        view.addSubview(stackView2)
        stackView2.frame = CGRect(x: 200, y: 50, width: 100, height: 150)
        
        // change to (0..<5) to see the stretching
        (0..<5).forEach {
            let label = UILabel()
            label.text = "text \($0)"
            label.backgroundColor = .red
            stackView2.addArrangedSubview(label)
        }
        
        p = 1000
        for v in stackView2.arrangedSubviews {
            v.setContentCompressionResistancePriority(UILayoutPriority(rawValue: p), for: .vertical)
            p -= 1
        }
        
        
        let cView1 = UIView()
        cView1.frame = CGRect(x: 50, y: 220, width: 100, height: 150)
        cView1.clipsToBounds = true
        
        // so we can see the view frame
        cView1.backgroundColor = .cyan
        
        view.addSubview(cView1)
        
        let stackView3 = UIStackView()
        stackView3.alignment = .leading
        stackView3.axis = .vertical
        
        cView1.addSubview(stackView3)
        
        stackView3.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            stackView3.topAnchor.constraint(equalTo: cView1.topAnchor),
            stackView3.leadingAnchor.constraint(equalTo: cView1.leadingAnchor),
            stackView3.trailingAnchor.constraint(equalTo: cView1.trailingAnchor),
        ])
        
        // change to (0..<5) to see NO stretching
        (0..<15).forEach {
            let label = UILabel()
            label.text = "text \($0)"
            label.backgroundColor = .red
            stackView3.addArrangedSubview(label)
        }
        
        let cView2 = UIView()
        cView2.frame = CGRect(x: 200, y: 220, width: 100, height: 150)
        cView2.clipsToBounds = true
        
        // so we can see the view frame
        cView2.backgroundColor = .cyan
        
        view.addSubview(cView2)
        
        let stackView4 = UIStackView()
        stackView4.alignment = .leading
        stackView4.axis = .vertical
        
        cView2.addSubview(stackView4)
        
        stackView4.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            stackView4.topAnchor.constraint(equalTo: cView2.topAnchor),
            stackView4.leadingAnchor.constraint(equalTo: cView2.leadingAnchor),
            stackView4.trailingAnchor.constraint(equalTo: cView2.trailingAnchor),
        ])
        
        // change to (0..<5) to see NO stretching
        (0..<5).forEach {
            let label = UILabel()
            label.text = "text \($0)"
            label.backgroundColor = .red
            stackView4.addArrangedSubview(label)
        }

    }
    
}

// Present the view controller in the Live View window
PlaygroundPage.current.liveView = PlaygroundFrankViewController()