ios UILabel在UIView中不可见

w41d8nur 于 2023-03-24 发布在 iOS

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无法在Swift、UIKit中以编程方式在UIView中添加UILabel

//
//  GlanceTableViewCell.swift
//
//  Created by Shivacharan Reddy on 23/03/23.
//

import UIKit

class GlanceTableViewCell: UITableViewCell {

    static let identifier = "GlanceTableViewCell"
    
    private let glanceView: UIView = {
        let view = UIView()
        view.backgroundColor = .gray
        view.layer.cornerRadius = 5
        view.layer.masksToBounds = true
        view.translatesAutoresizingMaskIntoConstraints = false
        return view
    }()
    
    private let mainLabel: UILabel = {
        let label = UILabel()
        label.font = .systemFont(ofSize: 15, weight: .bold)
        label.translatesAutoresizingMaskIntoConstraints = false
        label.textColor = .label
        label.backgroundColor = .white
        return label
    }()
    
    override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)
        
        contentView.addSubview(glanceView)
        
        glanceView.addSubview(mainLabel)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        
        glanceView.widthAnchor.constraint(equalToConstant: contentView.bounds.width - 10).isActive = true
        glanceView.heightAnchor.constraint(equalToConstant: contentView.bounds.height - 10).isActive = true
        glanceView.centerXAnchor.constraint(equalTo: contentView.centerXAnchor).isActive = true
        glanceView.centerYAnchor.constraint(equalTo: contentView.centerYAnchor).isActive = true
        
        mainLabel.leadingAnchor.constraint(equalTo: glanceView.leadingAnchor, constant: 5).isActive = true
        mainLabel.topAnchor.constraint(equalTo: glanceView.topAnchor, constant: 5).isActive = true
        mainLabel.widthAnchor.constraint(equalToConstant: glanceView.bounds.width / 2).isActive = true
        mainLabel.heightAnchor.constraint(equalToConstant: 100).isActive = true
        
    }
    
}

我想在glanceView中添加mainLabel，它的类型是UIView，但是当我运行代码时，我无法看到mainLabel，它甚至不可见。我在这里做错了什么？

ios

来源：https://stackoverflow.com/questions/75820970/the-uilabel-is-not-visible-inside-the-uiview

1条答案

按热度按时间

pu82cl6c1#

您将glanceView的高度与当前为零的contentView.bound相关联。

glanceView.heightAnchor.constraint(equalToConstant: contentView.bounds.height - 10).isActive = true

此外，glanceView的宽度为0，所以标签宽度将为零，这是因为glanceView不知道它的宽度，因为在您的其他约束中，您没有将标签的前导和尾随挂钩到它的边界，此外，即使您设置了上述约束，也还很早就要求它的边界

mainLabel.widthAnchor.constraint(equalToConstant: glanceView.bounds.width / 2).isActive = true

所以在这种情况下，您需要将它与ContentView宽度关联

mainLabel.widthAnchor.constraint(equalTo: contentView.widthAnchor, multiplier: 0.5),

要将代码重构为

class GlanceTableViewCell: UITableViewCell {

    static let identifier = "GlanceTableViewCell"
    
    private let glanceView: UIView = {
        
        let view = UIView()
        view.backgroundColor = .gray
        view.layer.cornerRadius = 5
        view.layer.masksToBounds = true
        view.translatesAutoresizingMaskIntoConstraints = false
        return view
    }()
    
    private let mainLabel: UILabel = {
        
        let label = UILabel()
        label.font = .systemFont(ofSize: 15, weight: .bold)
        label.translatesAutoresizingMaskIntoConstraints = false
        label.textColor = .label
        label.backgroundColor = .white
        return label
    }()
    
    override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)
        commonInit()
    }
    
    required init?(coder: NSCoder) {
        commonInit()
    }
    
    func commonInit() {
        
        contentView.addSubview(glanceView)
        glanceView.addSubview(mainLabel)
        
        NSLayoutConstraint.activate([
            glanceView.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: 10),
            glanceView.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -10),
            glanceView.topAnchor.constraint(equalTo: contentView.topAnchor, constant: 10),
            glanceView.bottomAnchor.constraint(equalTo: contentView.bottomAnchor, constant: -10),
            mainLabel.leadingAnchor.constraint(equalTo: glanceView.leadingAnchor, constant: 5),
            mainLabel.topAnchor.constraint(equalTo: glanceView.topAnchor, constant: 5),
            mainLabel.widthAnchor.constraint(equalTo: contentView.widthAnchor, multiplier: 0.5),
            mainLabel.heightAnchor.constraint(equalToConstant: 100)
        ])
    }
    
}

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ios UILabel在UIView中不可见

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