ios - 如何在代码中使用自动布局

Question

我想制作一个带有自动布局的自定义tableview，那么我该如何使用自动布局呢？

我觉得应该是这样的:-

self.view.addConstraints([
            NSLayoutConstraint(item: square, attribute: .width, relatedBy: .equal, toItem: nil, attribute: .width, multiplier: 1.0, constant: 64),
            NSLayoutConstraint(item: square, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .height, multiplier: 1.0, constant: 64),
            NSLayoutConstraint(item: square, attribute: .centerX, relatedBy: .equal, toItem: self.view, attribute: .centerX, multiplier: 1.0, constant: 0),
            NSLayoutConstraint(item: square, attribute: .centerY, relatedBy: .equal, toItem: self.view, attribute: .centerY, multiplier: 1.0, constant: 0),
        ])

Answer 1

嗨，我在我的一个项目中做了这件事:

这是VC的代码，你还需要为你的tableview单元格创建一个自定义类

import UIKit

class ViewController: UIViewController {

    //MARK:- view life cycle
    override func viewDidLoad() {
        super.viewDidLoad()
        self.configureTableView()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

    //Custom method
    func configureTableView(){
        let tblview = UITableView(frame: view.bounds, style: .plain)
        tblview.register(CustomTableViewCell.self, forCellReuseIdentifier: "CustomTableViewCell")
        tblview.delegate = self
        tblview.dataSource = self
        self.view.addSubview(tblview)
        }

    }

extension ViewController: UITableViewDataSource,UITableViewDelegate{

    func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
        return UITableViewAutomaticDimension
    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return 3
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

         let cell = CustomTableViewCell(style: .default, reuseIdentifier: "CustomTableViewCell")

         if indexPath.row == 0 {
            cell.backgroundColor = .gray
            cell.lblTitle.text = "Title"
            cell.lblDescription.text = "MessageMe"
            return cell
         }
        else if indexPath.row == 1{
            cell.backgroundColor = .green
            cell.lblTitle.text = "TitleTitleTitleTitleTitleTitle"
            cell.lblDescription.text = "MessageMe"
            return cell
         }
         else{
         cell.backgroundColor = .red
         cell.lblTitle.text = "Name"
         cell.lblDescription.text = "MessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessageMessag"
        return cell
        }
    }

}

这是自定义类的代码

 import UIKit

class CustomTableViewCell: UITableViewCell {

    //Cell View Object
    let imgUser = UIImageView()
    let lblTitle = UILabel()
    let lblDescription = UILabel()

    //constant
    let paddingWithContent:CGFloat = 20.0
    let gapBetweenObject:CGFloat = 10.0
    let heightWidthImage:CGFloat = 40.0
    let heightTitle:CGFloat = 25.0

    //Init
    override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)

        //cell object property
        imgUser.backgroundColor = .blue
        imgUser.contentMode = .scaleAspectFill
        lblDescription.numberOfLines = 0
        lblTitle.adjustsFontSizeToFitWidth = true
        lblTitle.minimumScaleFactor = 0.7

        //translatesAutoresizingMas
        imgUser.translatesAutoresizingMaskIntoConstraints = false
        lblTitle.translatesAutoresizingMaskIntoConstraints = false
        lblDescription.translatesAutoresizingMaskIntoConstraints = false

        //add to cell
        contentView.addSubview(imgUser)
        contentView.addSubview(lblTitle)
        contentView.addSubview(lblDescription)

        //add constraint
        NSLayoutConstraint.activate([
            //img
            imgUser.topAnchor.constraint(equalTo: contentView.topAnchor, constant: paddingWithContent),
            imgUser.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: paddingWithContent),
            imgUser.widthAnchor.constraint(equalToConstant: heightWidthImage),
            imgUser.heightAnchor.constraint(equalToConstant: heightWidthImage),

            //title lable
            lblTitle.topAnchor.constraint(equalTo: contentView.topAnchor, constant: paddingWithContent),
            lblTitle.leadingAnchor.constraint(equalTo: imgUser.leadingAnchor, constant: heightWidthImage + gapBetweenObject),
            lblTitle.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -paddingWithContent),
            lblTitle.heightAnchor.constraint(equalToConstant: heightTitle),

            //description label
            lblDescription.topAnchor.constraint(equalTo: lblTitle.bottomAnchor, constant: gapBetweenObject),
            lblDescription.bottomAnchor.constraint(equalTo: contentView.bottomAnchor, constant: -paddingWithContent),
            lblDescription.leadingAnchor.constraint(equalTo: imgUser.leadingAnchor, constant: heightWidthImage + gapBetweenObject),
            lblDescription.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -paddingWithContent),

            ])
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }

}