Question

我尝试为服务器创建包含Background和Main队列的请求方法。最后，此方法应从服务器返回NSDictionary我的响应。

func sendRequest(UrlString urlString:String,MethodString method:String)->(NSDictionary)  {

    DispatchQueue.global(qos: .background).async {
        var request = URLRequest(url: URL(string:urlString)!)
        request.httpMethod = method
        //let postString = "id=13&name=Jack"
        //request.httpBody = postString.data(using: .utf8)
        let task = URLSession.shared.dataTask(with: request) { data, response, error in
            guard let data = data, error == nil else {                                                 // check for fundamental networking error
                print("error=\(error)")
                return
            }

            if let httpStatus = response as? HTTPURLResponse, httpStatus.statusCode != 200 {           // check for http errors
                print("statusCode should be 200, but is \(httpStatus.statusCode)")
                print("response = \(response)")
            }

            let responseString = String(data: data, encoding: .utf8)
            print("responseString = \(responseString)")

        DispatchQueue.main.async {

            do {
                let jsonDictionary:NSDictionary = try JSONSerialization.jsonObject(with: data, options: []) as! [String: AnyObject] as NSDictionary

                return jsonDictionary

            } catch {
                //Handle the error
            }

            //return airports
        }

    }

    task.resume()
}

现在当尝试在主队列中返回jsonDictionary时，它会向我显示此错误：

void函数中出现意外的非void返回值

现在我不知道如何解决这个问题我使用的是Xcode 8，iOS8和Swift 3 请帮帮我谢谢。

Answer 1

您已实施至少两个异步操作，但它们无法返回值。对于异步操作，您应该使用如下的完成处理程序：

func sendRequest(urlString: String, method: String, completion: @escaping (_ dictionary: NSDictionary?, _ error: Error?) -> Void) {

    DispatchQueue.global(qos: .background).async {
        var request = URLRequest(url: URL(string:urlString)!)
        request.httpMethod = method
        let task = URLSession.shared.dataTask(with: request) { data, response, error in
            guard let data = data, error == nil else {                                                 // check for fundamental networking error
                print("error=\(error)")
                completion(nil, error)
                return
            }

            if let httpStatus = response as? HTTPURLResponse, httpStatus.statusCode != 200 {           // check for http errors
                print("statusCode should be 200, but is \(httpStatus.statusCode)")
                print("response = \(response)")
                // make error here and then
                completion(nil, error)
                return
            }

            let responseString = String(data: data, encoding: .utf8)
            print("responseString = \(responseString)")

            DispatchQueue.main.async {
                do {
                    let jsonDictionary:NSDictionary = try JSONSerialization.jsonObject(with: data, options: []) as! [String: Any] as NSDictionary

                    completion(jsonDictionary, nil)

                } catch {
                    completion(nil, error)
                }
            }

        }

        task.resume()
    }
}

请求服务器iOS Swift 3中的void函数中出现意外的非void返回值

1 个答案: