通过 UIButton 使用自定义 TableViewCell 添加到收藏夹并保存到 UserDefaults

如何解决通过 UIButton 使用自定义 TableViewCell 添加到收藏夹并保存到 UserDefaults

目标：在自定义 TableViewCell 中创建一个“添加到收藏夹”按钮，然后将收藏夹列表保存到 UserDefaults 中，以便我们只能获得收藏夹的 tableview。（我使用 segmentedControl 作为过滤 where libraryFilter = 0(Plan) / 1 = Tag / 2 = Duration / 3 = Favorite）

jsonErgWorkouts 是来自 JSON 文件的锻炼数组，它是过滤的基础。

这是我编写的代码。

自定义 TableViewCell：

import UIKit

class ErgWorkoutCell: UITableViewCell {
  
  @IBOutlet weak var ergWorkoutTitle: UILabel! 
}

在 TableView 视图控制器中

  func tableView(_ tableView: UITableView,cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let selectedGroup = selectedWorkoutGroup(libraryFilter: libraryFilter,jsonErgWorkouts: jsonErgWorkouts,workoutGroupBox: workoutGroupBox)
    
    /// this is cast AS! ErgWorkoutCell since this is a custom tableViewCell
    let cell = tableView.dequeueReusableCell(withIdentifier: "ergWorkoutCell") as! ErgWorkoutCell
    
    cell.ergWorkoutTitle.text = selectedGroup[indexPath.row].title
    return cell
  }
}


func selectedWorkoutGroup(libraryFilter: Int,jsonErgWorkouts:[workoutList],workoutGroupBox: UITextField) -> [workoutList] {
  var selectedGroup = [workoutList]()
    
  if libraryFilter == 0 { // Segmented Control #1 (Plan)
    selectedGroup = jsonErgWorkouts.filter { $0.group == workoutGroupBox.text }
  /// code for libraryFilter 1(Tag)
  ///      and libraryFilter 2(Duration) 
  } else if libraryFilter == 3 {
    // Need code here to return the filtered JSON of favorites only
  }
  
  return selectedGroup
}

解决方法

需要做的事情很少。我还将链接一些有助于获得此解决方案的 SO 页面。

在故事板中添加按钮
在自定义 TableViewCell 中添加一个按钮定义（IBOutlet/IBAction）和一个闭包
添加一种将所选收藏夹存储到 UserDefaults 中的方法
在 segmentedControl 中显示收藏夹列表。

让我们开始吧：

向情节提要中添加按钮

我会把这个留给用户

在自定义 TableViewCell 中添加一个按钮定义（IBOutlet/IBAction）和一个闭包

import UIKit
class ErgWorkoutCell: UITableViewCell {

  @IBOutlet weak var ergWorkoutTitle: UILabel!

  /// Create and Connect your Button outlet
  @IBOutlet weak var ergWorkoutFavBtn: UIButton!

  /// create your closure here
  /// https://stackoverflow.com/a/55743790/14414215
  var favButtonPressed : (() -> ()) = {}

  /// Create & Connect an IBAction when your button is pressed. 
  @IBAction func ergWorkoutFavBtn(_ sender: UIButton) {
    /// Call your closure here
    favButtonPressed()
  }
}

添加一种将所选收藏夹存储到 UserDefaults 中的方法

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

/// https://stackoverflow.com/a/37357869/14414215
/// https://stackoverflow.com/q/65355061/14414215
/// Provide an initial default (empty array) to the UserDefaults Array since on startup there is no fav in the list.
var rowsWhichAreChecked = UserDefaults.standard.array(forKey: "workoutFavorite") as? [Int] ?? [Int]()

/// this is cast AS! ErgWorkoutCell since this is a custom tableViewCell
let cell = tableView.dequeueReusableCell(withIdentifier: "ergWorkoutCell") as! ErgWorkoutCell

cell.ergWorkoutTitle.text = selectedGroup[indexPath.row].title

/// This is to change the image between favourited or Not
if rowsWhichAreChecked.contains(selectedGroup[indexPath.row].id) {
  cell.ergWorkoutFavBtn.setImage(#imageLiteral(resourceName: "star-full"),for: .normal)
} else {
  cell.ergWorkoutFavBtn.setImage(#imageLiteral(resourceName: "star-empty"),for: .normal)
}

/// https://stackoverflow.com/a/55743790/14414215
/// Once the FavButton is pressed,we determine if the selected item is already 
/// in the FavList. If Yes,we remove it,if Not,we add it in.
/// We then reload the table
/// Added [ weak self] in based on @azehe
/// https://stackoverflow.com/q/64297651/14414215
cell.favButtonPressed = { [ weak self ] in
  if rowsWhichAreChecked.contains(selectedGroup[indexPath.row].id) {
    let removeIdx = rowsWhichAreChecked.lastIndex(where: {$0 == selectedGroup[indexPath.row].id})
    rowsWhichAreChecked.remove(at: removeIdx!)

    cell.ergWorkoutFavBtn.setImage(#imageLiteral(resourceName: "star-empty"),for: .normal)
  } else {
    cell.ergWorkoutFavBtn.setImage(#imageLiteral(resourceName: "star-full"),for: .normal)
    rowsWhichAreChecked.append(selectedGroup[indexPath.row].id)
  }
  UserDefaults.standard.set(rowsWhichAreChecked,forKey: "workoutFavorite")
  self?.vcLibTableView.reloadData() // self? instead of self (with [weak self] in
}
  return cell
}

在 segmentedControl 中显示收藏夹列表。

   func selectedWorkoutGroup(libraryFilter: Int,jsonErgWorkouts:[workoutList],workoutGroupBox: UITextField) -> [workoutList] {
     var selectedGroup = [workoutList]()
     
     /// https://stackoverflow.com/a/37357869/14414215
     let workoutFav = UserDefaults.standard.array(forKey: "workoutFavorite") as? [Int] ?? [Int]()

     if libraryFilter == 0 {
       selectedGroup = jsonErgWorkouts.filter { $0.group == workoutGroupBox.text }
     } else if libraryFilter == 1 {
       /// https://stackoverflow.com/q/65355061/14414215
       selectedGroup = workoutFav.flatMap { favouriteId in // for each favourite ID
             jsonErgWorkouts.filter { $0.id == favouriteId }
      } // flatMap joins all those arrays returns by "filter" together,no need to do anything else
     }
     
     return selectedGroup
   }

根据@azehe 评论的输入添加 [weak self] in 。您可以在内存图中看到差异。