无法在强制转换中将 '_?' 类型的值转换为 '[AFTParty]?' 类型 - Swift

Question

我正在读取一个返回对象数组的JSON。我想将JSON响应绑定到我的对象AFTPParty，但我遇到了以下编译错误：

无法转换类型为"_？"的值键入"[AFTParty]？"

AFTPParty是一个符合可解码协议的类，我使用Himotoki来完成这项工作。

我的JSON:

[
{
id: 1,
partyName: "x",
partyAuthor: [
{
id: 1,
username: "mtfons",
name: "marco",
lastname: "fonseca",
phoneNumber: "91859158",
email: "[e-mail]"
}
],
partyDescription: null,
partyStyle: null,
partyPermission: "PUBLICA",
partyLocation: {
id: 1,
latitude: "1248174",
longitude: "1428149"
},
prices: [ ],
partyDetailToJoin: "x",
partyDateBegin: null,
partyDateEnd: null,
partyImagesPath: [ ],
partyParticipants: [
{
id: 1,
username: "x",
name: "x",
lastname: "x",
phoneNumber: "x",
email: "[e-mail]"
},
{
id: 2,
username: "x",
name: "ajfk",
lastname: "jfa",
phoneNumber: "x",
email: "[e-mail]"
}
],
time: null,
partyType: null
}
]

导致错误的代码：

      let partyDeserializer = AFTPartyDeserializerImplementation(network: network)
            describe("Response") {
                it("returns party if the network works correctly.") {
                    var response = [AFTParty]()
                    partyDeserializer.getParty().on(next: { response = $0 }).start()
                }
     }

       public func getParty() -> SignalProducer<AFTParty, AFTNetworkError> {
            let url = AFTRouter.Parties.URL
            return network.requestJSON(url, parameters: nil)
                .attemptMap { json in
                    if let response = (try? decodeValue(json)) as [AFTParty]? {
                        return Result(value: response)
                    }
                    else {
                        return Result(error: .IncorrectDataReturned)
                    }
            }
        }

谢谢你的帮助，我很抱歉我的英语不好。

Answer 1

你是说吗

public func getParty() -> SignalProducer<[AFTParty], AFTNetworkError> {

Answer 2

如果decodeValue(json)返回AnyObject，那么您可能希望使用as?而不是as进行强制转换。