Swift 调用的结果未被使用

Question

我不知道如何在 swift3 中删除此警告：

调用 'responseMessagesArray' 的结果未使用

我的代码是这样的：

fileprivate class func getMessagesAtPath(_ path: String, tokenKey: String, completionHandler: @escaping (MyMessagesWrapper?, NSError?) -> Void) {
        let credentialData = ":\(tokenKey)".data(using: String.Encoding.utf8)!
        let base64Credentials = credentialData.base64EncodedString(options: [])

        let headers = ["Accept": "application/json",
                       "Content-Type": "application/json",
                       "Authorization": "Basic \(base64Credentials)"]

        Alamofire.request(path, headers: headers)
            .responseMessagesArray { response in
                if let error = response.result.error
                {
                    completionHandler(nil, error as NSError?)
                    return
                }
                completionHandler(response.result.value, nil)
        }
    }

    class func getMyMessages(_ completionHandler: @escaping (MyMessagesWrapper?, NSError?) -> Void) {
        getMessagesAtPath(MyMessages.endpointForMyMessages(),tokenKey: MyMessages.getTokenKey(),completionHandler: completionHandler)
    }

extension Alamofire.DataRequest {
    func responseMessagesArray(_ completionHandler: @escaping (DataResponse<MyMessagesWrapper>) -> Void) -> Self {
        let responseSerializer = DataResponseSerializer<MyMessagesWrapper> { request, response, data, error in
            guard error == nil else
            {
                return .failure(error!)
            }
            guard let responseData = data else {
                return .failure(AFError.responseSerializationFailed(reason: .inputDataNil))

            }

            let JSONResponseSerializer = DataRequest.jsonResponseSerializer(options: .allowFragments)
            let result = JSONResponseSerializer.serializeResponse(request, response, responseData, error)

            switch result {
            case .success(let value):
                let json = JSON(value)
                let wrapper = MyMessagesWrapper()

                wrapper.next = json["messages"]["next_page_url"].stringValue
                wrapper.previous = json["messages"]["prev_page_url"].stringValue
                wrapper.count = json["messages"]["total"].intValue

                var allMessages:Array = Array<MyMessages>()
                print(json)
                let results = json["messages"]["data"]
                //print(results)
                for jsonAds in results
                {
                    //print(jsonAds.1)
                    let mesaggesData = MyMessages(json: jsonAds.1, id: Int(jsonAds.0))
                    allMessages.append(mesaggesData)
                }
                wrapper.myMessages = allMessages
                return .success(wrapper)
            case .failure(let error):
                return .failure(error)
            }
        }

        return response(responseSerializer: responseSerializer,
                        completionHandler: completionHandler)
    }
}

我从 fileprivate class func getMessagesAtPath() 收到警告就在 .responseMessagesArray { 响应 出现的地方

我在 swift 2.

中从未收到过此警告

Answer 1

将函数的 return 值赋给 _ 以显式丢弃它，像这样：

_ = somethingThatReturnsAValueYouDontCareAbout()

Swift 3 警告未使用的函数 return 值，因此您需要向它表明您知道自己在做什么。

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