swift 4 : struct in struct

Question

我在创建结构时遇到问题。

我的结构:

public struct Device: Codable {
    let data: DeviceData
    let meta: Meta?
}

public struct DeviceData: Codable {
    let deviceID: String?
    let type: String?
    let attributes: Attributes?

    private enum CodingKeys: String, CodingKey {
        case deviceID = "id"
        case type
        case attributes
    }
}

public struct Attributes: Codable {
    let name: String?
    let asdf: String?
    let payload: Payload?
}

public struct Payload: Codable {
    let example: String?
}

public struct Meta: Codable {
    let currentPage: Int?
    let nextPage: Int?
    let deviceID: [String]?
}

当我现在想创建这个结构的一个元素时:

var exampleData = Device(
        data: DeviceData(
            type: "messages",
            attributes: Attributes(
                name: "Hello World",
                asdf: "This is my message",
                payload: Payload(
                    example: "World"
                )
            )
        ),
        meta: Meta(
            deviceID: ["asfd-asdf-asdf-asdf-asdfcasdf"]
        )
    )

我会得到一个错误。无法详细说明此错误，因为当我删除“meta”元素时，因为它是可选的，所以会发生另一个错误...此特定代码的错误消息是:

Extra argument 'meta' in call

我希望有人能帮助我。

Answer 1

您忘记了 deviceID: 调用 DeviceData.init(deviceID:type:attributes:) 的命名参数，并且您也忘记了 currentPage 和 nextPage 将参数命名为 Meta.init(currentPage:nextPage:deviceID)。

这是一个编译示例:

var exampleData = Device(
    data: DeviceData(
        deviceID: "someID",
        type: "messages",
        attributes: Attributes(
            name: "Hello World",
            asdf: "This is my message",
            payload: Payload(
                example: "World"
            )
        )
    ),
    meta: Meta(
        currentPage: 123,
        nextPage: 456,
        deviceID: ["asfd-asdf-asdf-asdf-asdfcasdf"]
    )
)