ios - 将 Set<CustomObject> 存储到 UserDefaults

Question

我有一个自定义类，用作 Set<ListItem> .我想将其存储到 userDefaults。但是，我得到 Attempt to set a non-property-list object as an NSUserDefaults尝试时出错。我试图将其更改为 Array然后保存它但仍然是同样的错误。在看到一些帖子后，我也尝试了另存为数据，这又给了我以下错误。

NSForwarding: warning: object 0x600003bf9a00 of class 'iTunes_Search_Me.ListItem' does not implement methodSignatureForSelector: -- trouble ahead

class ListItem: Codable ,Equatable, Hashable {
    let wrapperType, kind: String?
    let artistID, collectionID, trackID: Int?
    let artistName, collectionName, trackName: String?
    let trackViewURL: String?
    let artworkUrl30, artworkUrl60, artworkUrl100: String?
    let releaseDate: String?
    let primaryGenreName: String?
    var isSelected: Bool = false
    enum CodingKeys: String, CodingKey {
        case wrapperType, kind
        case artistID
        case collectionID
        case trackID
        case artistName, collectionName, trackName
        case trackViewURL
        case artworkUrl30, artworkUrl60, artworkUrl100, releaseDate, primaryGenreName
    }

    static func ==(lhs: ListItem, rhs: ListItem) -> Bool {
        return lhs.trackID == rhs.trackID
    }

    func hash(into hasher: inout Hasher) {
        hasher.combine(trackID)
    }
}

Attempt to set a non-property-list object as an NSUserDefaults

Answer 1

您可以像这样将模型设置为 UserDefaults:

• 首先您应该创建模型的实例

• 然后您可以将模型保存到 UserDefaults:

  let encoder = JSONEncoder()
  if let encoded = try? encoder.encode(listItemInstance) {
      let defaults = UserDefaults.standard
      defaults.set(encoded, forKey: "ListItemObject")
  }
  

  您可以像这样从 UserDefaults 获取模型

  if let savedItem = defaults.object(forKey: "ListItemObject") as? Data {
      let decoder = JSONDecoder()
      if let loadedItem = try? decoder.decode(ListItem.self, from: savedItem) {
          print(loadedItem)
      }
  }