通话中出现额外的参数“错误”-无法构建我的Xcode项目

Question

import Foundation

class NetworkOperation {

    lazy var config: NSURLSessionConfiguration =     NSURLSessionConfiguration.defaultSessionConfiguration()
    lazy var session: NSURLSession = NSURLSession(configuration: self.config)
    let queryURL: NSURL

    typealias JSONDictionaryCompletion = ([String: AnyObject]? -> Void)

    init(url: NSURL) {
        self.queryURL = url
    }

    func downloadJSONFromURL(completion: JSONDictionaryCompletion) {

        let request = NSURLRequest(URL: queryURL)
        let dataTask = session.dataTaskWithRequest(request) {
            (let data, let response, let error) in

// 1.检查HTTP响应以获取成功的GET请求

            if let httpResponse = response as? NSHTTPURLResponse {
                switch httpResponse.statusCode {
                case 200:

// 2.使用数据创建JSON对象

                    let jsonDictionary = NSJSONSerialization.JSONObjectWithData(data, options: nil, error: nil)
                    completion(jsonDictionary)
                default:
                    print("GET request not successful. HTTP status code: \(httpResponse.statusCode)")
                }
            } else {
                print("Error: Not a valid HTTP response")
            }
        }

        dataTask.resume()
    }
}

在“使用数据创建JSON对象”步骤中，我不断收到“调用中的额外参数'error'”。 怎么了？ 我找不到文档来进一步帮助我。

Answer 1

您可以通过这种方式做到这一点。

do{
        var jsonDictionary  = try NSJSONSerialization.JSONObjectWithData(data, options:NSJSONReadingOptions.MutableContainers)
        //completion(jsonDictionary)
    }catch{
       // report error
    }

Answer 2

在步骤2的顶部：创建json ....

添加此行：

var err: NSError?

Answer 3

// 1.检查HTTP响应以获取成功的GET请求

            if let httpResponse = response as? NSHTTPURLResponse {
                switch httpResponse.statusCode {
                case 200:

// 2.使用数据创建JSON对象

                    let jsonDictionary = NSJSONSerialization.JSONObjectWithData(data, options: nil, error: nil) as? [String: AnyObject]
                    completion(jsonDictionary)
                default:
                    println("GET request not successful. HTTP status code: \(httpResponse.statusCode)")
                }
            } else {
                println("Error: Not a valid HTTP response")
            }
        }

        dataTask.resume()
    }
}

终于想通了！ 谢谢大家的投入！