使用自定义 UITableViewCell 添加到收藏夹到 UIButton 并保存到 UserDefaults

Question

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，这样我们就可以只获得收藏夹的表格视图。 （我使用 segmentedControl 作为过滤 libraryFilter = 0(Plan) / 1 = Tag / 2 = Duration / 3 = Favorite 的方法）

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
}

Answer 1

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。

1. 在情节提要中添加一个按钮
2. 在自定义 TableViewCell 中添加一个按钮定义（IBOutlet/IBAction）和一个闭包
3. 添加将所选收藏夹存储到 UserDefaults 中的方法
4. 在 segmentedControl 中显示收藏夹列表。

让我们开始吧：

1. 在情节提要中添加一个按钮

   我会把这个留给用户

2. 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()
     }
   }
   

3. 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
   }
   

4. 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。