使用 Realm swift 初始化列表值

Question

我正在尝试初始化几个对象，其中包括列表对象，但我不确定确切的语义是什么。是否可以从 Realm 对象中初始化 List 对象，或者我是否必须以其他方式附加它们？

class ResourcesData: Object {
    @objc dynamic var resourceID = UUID().uuidString
    @objc dynamic var name = "";

    let valueSemantics = List<ValueSemantics>();

    convenience init(resourceName: String, semantics: List<ValueSemantics>) {
        self.init()
        self.name = resourceName
        self.valueSemantics = semantics
    }

    override static func primaryKey() -> String? {
        return "resourceID"
    }
}

我的列表模型与初始值设定项

class ValueSemantics: Object {
    @objc dynamic var name = "";
    @objc dynamic var value = 0;

    convenience init(value: Int, valueName: String) {
        self.init()
        self.name = valueName
        self.value = value
    }
}

这是我尝试初始化对象的方法，但它抛出以下错误'<' is not a postfix unary operator

let data: [ResourcesData] = [
  ResourcesData(resourceName: "Iron ore",
                semantics: List<
                  ValueSemantics(value: 0, valueName: "None"),
                  ValueSemantics(value: 1, valueName: "Average")
                  >
  ),
  ResourcesData(resourceName: "Gold ore",
                semantics: List<
                  ValueSemantics(value: 0, valueName: "None"),
                  ValueSemantics(value: 1, valueName: "Average")
                  >
  )   
];

do {
    try realm.write {
        realm.add(data);
    }
}catch {
    print("Error starting Realm! \(error)");
}

我也尝试通过以下方式初始化它

ResourcesData(resourceName: "Gold ore",
                    semantics: List(
                      ValueSemantics(value: 0, valueName: "None"),
                      ValueSemantics(value: 1, valueName: "Average")
                      ))

也

ResourcesData(resourceName: "Gold ore",
                    semantics: [
                                ValueSemantics(value: 0, valueName: "None"),
                                ValueSemantics(value: 1, valueName: "Average")])

Answer 1

List只有一个空的初始值设定项，因此向 a 添加值的唯一方法List是使用append. 您最好修改 的初始化程序ResourcesData以接受Array并调用append(contentsOf:)以将数组的元素添加到列表中。

class ResourcesData: Object {
    @objc dynamic var resourceID = UUID().uuidString
    @objc dynamic var name = ""

    let valueSemantics = List<ValueSemantics>()

    convenience init(resourceName: String, semantics: [ValueSemantics]) {
        self.init()
        self.name = resourceName
        self.valueSemantics.append(objectsIn: semantics)
    }

    override static func primaryKey() -> String? {
        return "resourceID"
    }
}

然后你可以像这样初始化它：

let data: [ResourcesData] = [
  ResourcesData(resourceName: "Iron ore",
                semantics: [ValueSemantics(value: 0, valueName: "None"),
                  ValueSemantics(value: 1, valueName: "Average")]
  ),
  ResourcesData(resourceName: "Gold ore",
                semantics: [ValueSemantics(value: 0, valueName: "None"),
                  ValueSemantics(value: 1, valueName: "Average")]
  )   
]

与你的问题无关，但你不应该在 Swift 中的行尾放置分号，这不是 Objective-C。