Swift 5 UIStackView中添加自动换行的Label

说明

实现UIStackView中添加可以自动换行的Label

思路分析：

1. view中添加UIStackView，UIStackView添加Label;
2. UIStackView的constraint为上，左，右；
3. Label的constraint为左，右；Label的numberOfLine = 0

Demo 代码如下：

//
//  ViewController.swift
//  StackViewLabelDemo
//
//  Created by zgpeace on 2021/3/23.
//

import UIKit

class ViewController: UIViewController {
    
    
    
    private lazy var stackView: UIStackView = {
    
    
        let stackView = UIStackView()
        stackView.translatesAutoresizingMaskIntoConstraints = false
//        stackView.alignment = .center
        stackView.axis = .horizontal
        stackView.distribution = .fill
        
        return stackView
    }()
    
    private lazy var label: UILabel = {
    
    
        let label = UILabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        label.numberOfLines = 0
        label.lineBreakMode = .byWordWrapping
        label.font = UIFont.systemFont(ofSize: 16)
        label.textColor = .orange
        
        return label
    }()

    override func viewDidLoad() {
    
    
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        
        setupViews()
    }
    
    private func setupViews() {
    
    
        self.view.translatesAutoresizingMaskIntoConstraints = false
        self.view.addSubview(stackView)
        stackView.addArrangedSubview(label)
        label.text = """
            For a horizontal stack view that has a UILabel as one of its views, in Interface Builder firstly set label.numberOfLines = 0. This should allow the label to have more than 1 line. This initially failed to work for me when the stack view had stackView.alignment = .fill. To make it work simply set stackView.alignment = .center. The label can now expand to multiple lines within the UIStackView.

            The Apple documentation says

            For all alignments except the fill alignment, the stack view uses each arranged view’s intrinsic​Content​Size property when calculating its size perpendicular to the stack’s axis

            Note the word except here. When .fill is used, the horizontal UIStackView does NOT resize itself vertically using the arranged subviews' sizes.
        """
        
        NSLayoutConstraint.activate([
            stackView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor),
            stackView.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 8.0),
            stackView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -8.0),
            
            label.leadingAnchor.constraint(equalTo: stackView.leadingAnchor),
            label.trailingAnchor.constraint(equalTo: stackView.trailingAnchor)
//            label.topAnchor.constraint(equalTo: stackView.topAnchor),
//            label.bottomAnchor.constraint(equalTo: stackView.bottomAnchor)
        ])
    }


}

参考

https://stackoverflow.com/questions/34386528/multiline-label-in-uistackview