如何在Swift 3中更新字典的键

Question

if (userFollowingArray[indexPath.row]["watcher_following"] as! Bool) == false {
    let dict : NSMutableDictionary = userFollowingArray[indexPath.row] as! NSMutableDictionary
    print(dict)
    dict["watcher_following"] = 1
    self.userFollowingArray[indexPath.row] = dict as! Dictionary<String, Any>
}

我想用watcher_following更新true/false密钥，但会引发异常。

  

[_ TtGCs26_SwiftDeferredNSDictionarySSP__   _swift_setObject：forKeyedSubscript：]：无法识别的选择器发送到实例

Answer 1

不要在Swift

中使用NSMutable...集合类型

• 将userFollowingArray声明为Swift数组

  var userFollowingArray = [[String:Any]]()
  

• 获取Dictionary var iable

  var dict = userFollowingArray[indexPath.row]
  

• 检查值

  if dict["watcher_following"] as! Bool == false {
  

• 如有必要，请更新它并将字典分配回数组。

      dict["watcher_following"] = true
      userFollowingArray[indexPath.row] = dict
  }
  

  由于价值语义，最后一步是必要的

使用自定义结构或类而不是指南针更加方便。

Answer 2

为可变类型声明var，let仅用于不可变/常量类型。不需要使用目标c NSMutableDictionary类型。

if dict["watcher_following"] as! Bool == false {
    var dict : Dictionary<String, Any> = userFollowingArray[indexPath.row] as! Dictionary<String, Any>
    dict["watcher_following"] = 1
    self.userFollowingArray[indexPath.row] = dict as! Dictionary<String, Any>
}