如何在Swift 4中保留Realm List属性? [英] How to persist a Realm List property in Swift 4?

问题描述

使用Swift 4和Realm 3.0.1，我想将Realm对象的列表存储在父Realm的属性中 目的.我遇到了以下问题:

Using Swift 4 and Realm 3.0.1, I'd like to store a list of Realm objects in a property of a parent Realm object. I ran into the following problem:

在Swift 4中，应保留在Realm中的属性必须为@objc dynamic，例如@objc dynamic var id: String = "".但是，无法以这种方式存储Realm的Array替换类型List:@objc dynamic var children: List<Child>? = nil导致此编译器错误:

In Swift 4, properties that should be persisted into Realm have to be @objc dynamic, e.g. @objc dynamic var id: String = "". However, Realm's Array replacement type, List, can not be stored that way: @objc dynamic var children: List<Child>? = nil causes this compiler error:

无法将属性标记为@objc，因为其类型无法在Objective-C中表示

Property cannot be marked @objc because its type cannot be represented in Objective-C

有关更多背景信息，请参见以下完整示例:

For more context, here's a full example:

final class Child: Object {
  @objc dynamic var name: String = ""
}

final class Parent: Object {
  // this fails to compile
  @objc dynamic var children1: List<Child>?

  // this compiles but the children will not be persisted
  var children2: List<Child>?
}

那么还有另一种在Realm和Swift 4中存储对象列表的方法吗?

So is there another way to store object lists in Realm and Swift 4?

推荐答案

领域List永远不能是nil，并且它们不需要@objc dynamic.它们只能是let，尽管我在文档中找不到特别注明的内容，但是有一个

Realm Lists can never be nil, and they don’t need the @objc dynamic. They should only be let, although I can't find that specifically called out in the documentation, there is a comment from a realm contributor that calls it out specifically

对于文档.

let dogs = List<Dog>()

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