在 NSUserDefaults 的表格视图单元格中保存收藏按钮的状态

Posted 2023-03-12

【中文标题】在 NSUserDefaults 的表格视图单元格中保存收藏按钮的状态

【英文标题】：Save state of favorite button in Table view Cell in NSUserDefaults

【发布时间】：2017-08-04 04:30:54

【问题描述】：

我已经为这类问题经历了很多解决方案，但我仍然卡住了，不知道如何将按钮的状态保存到 NSUserDefaults 中。

Here is the picture for demo

这是我的 Tableview 控制器

override func viewDidLoad() 

    super.viewDidLoad()
    navigationItem.title = "Contacts"
    tableView.register(RecordCell.self, forCellReuseIdentifier: "cellId")



override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell 
    let myCell = tableView.dequeueReusableCell(withIdentifier: "cellId", for: indexPath as IndexPath) as! RecordCell


    myCell.starButton.tag = indexPath.row
    myCell.myTableViewController = self
    return myCell

这是我的自定义 Cell 类

class RecordCell: UITableViewCell 

var myTableViewController: HomepageController?

override init(style: UITableViewCellStyle, reuseIdentifier: String?) 
    super.init(style: style, reuseIdentifier: reuseIdentifier)
    setupViews()


required init?(coder aDecoder: NSCoder) 
    fatalError("init(coder:) has not been implemented")


let nameLabel: UILabel = 
    let label = UILabel()
    label.translatesAutoresizingMaskIntoConstraints = false
    label.font = UIFont (name: "SFCompactDisplay-Regular", size: 14)
    return label
()
let companyLabel: UILabel = 
    let label = UILabel()
    label.translatesAutoresizingMaskIntoConstraints = false
    label.font = UIFont (name: "SFCompactDisplay-Light", size: 10)
    return label
()
let shortname: UILabel = 
    let label = UILabel()
    label.textColor = UIColor.white
    label.translatesAutoresizingMaskIntoConstraints = false
    label.font = UIFont (name: "SFCompactDisplay-Regular", size: 12)
    label.textAlignment = .center
    label.backgroundColor = UIColor(patternImage: UIImage(named: "avatar")!)
    return label
()
let starButton: UIButton = 
    let button = UIButton(type: .system)
    button.setImage(UIImage(named: "star"), for: .normal)
    button.translatesAutoresizingMaskIntoConstraints = false
    return button
()
let playButton: UIButton = 
    let button = UIButton(type: .system)
    button.setImage(UIImage(named: "playback"), for: .normal)
    button.translatesAutoresizingMaskIntoConstraints = false
    return button
()

func setupViews() 
    addSubview(nameLabel)
    addSubview(companyLabel)
    addSubview(shortname)
    addSubview(starButton)
    addSubview(playButton)

    starButton.addTarget(self, action: #selector(RecordCell.starAction), for: .touchUpInside)

// playButton.addTarget(self, action: #selector(RecordCell.playAudio), for: .touchUpInside)

    addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-8-[v4(40)]-8-[v0]-8-[v1(30)]-8-[v2(30)]-8-|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": nameLabel, "v1": starButton,"v2":playButton, "v4":shortname]))
    addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-56-[v3]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v3": companyLabel]))


    addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|-2-[v0][v3]-7-|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": nameLabel,"v3": companyLabel]))
    addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": starButton]))
    addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": playButton]))
    addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|-2-[v0(40)]-7-|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": shortname]))



func starAction() 
    starButton.setImage(UIImage(named:"star-active"), for: .normal)

【问题讨论】：

一个建议。将按钮的状态存储在用户默认值中并不是一个好的编程习惯。如果您真的想（重新）存储按钮的状态，更好的方法是创建一个单例类并将按钮的当前状态写入其中。

我是 Swift 新手，对单例模式一无所知。我只是尝试一些简单的东西。顺便说一句，非常感谢你的建议。我稍后会考虑

【参考方案1】：

在RecordCell类中添加标签作为变量

class RecordCell: UITableViewCell 

var myTableViewController: HomepageController?
var favID:Int = 0
.....//other code

在视图控制器

中

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell 
    let myCell = tableView.dequeueReusableCell(withIdentifier: "cellId", for: indexPath as IndexPath) as! RecordCell

    myCell.favID = indexPath.row //set value to favID variable
    myCell.myTableViewController = self
    myCell.updateSelection() //call this method to update the selection
    return myCell

在 RecordCell 类中

override func awakeFromNib() 
    super.awakeFromNib()
    updateSelection()


func updateSelection() 
    let key = "\(favID)" 
    let userDefault = UserDefault.standard
    let isFav = userDefault.bool(forKey: key)
    starButton.isSelected = isFav


let starButton: UIButton = 
    let button = UIButton(type: .system)
    button.setImage(UIImage(named: "star"), for: .normal) //add image for different states
    button.setImage(UIImage(named:"star-active"), for: .selected) //add image for different states
    button.translatesAutoresizingMaskIntoConstraints = false
    return button
()

func setupViews() 
    ....
    ....//other code
    updateSelection()


func starAction() 
    starButton.isSelected = !starButton.isSelected //toggle selection
    let key = "\(favID)" 
    let userDefault = UserDefault.standard
    userDefault.set(starButton.isSelected, forKey: key)
    userDefault.synchronize()

这是一个基于索引的示例，如果可能，您可以使用表中显示的对象的任何唯一标识符作为键。或者在数据模型本身中设置一个 isFav 变量。

【讨论】：

感谢您的回复，它确实切换但状态未正确保存，我认为可能是索引路径的问题

你有多个部分吗？现在保存的行为如何？

点击任意一行中的一个按钮，它不会只保存该行的状态，如果我点击切换所有按钮，它会保存所有

希望您使用isSelected而不是在答案中选择'

是的，现在可以使用了。非常感谢你拯救了我的一天

【参考方案2】：

func starAction() 

     let userDefault = UserDefault.standard
      userDefault.set(true, forKey: "KEY_IS_SELECTED")
    starButton.setImage(UIImage(named:"star-active"), for: .normal)

获取最喜欢的按钮状态：

let userDefault = UserDefault.standard
let state = userDefault.bool(forKey: "KEY_IS_SELECTED")

//get stored state of button
//use state of button

【讨论】：

感谢您的回复，但问题是我希望用户可以根据 isSelected 属性切换按钮的状态然后保存。也基于联系人的每一行