调用中的额外参数 'error' - 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. 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'Create JSON object with data'步，我一直收到"extra argument 'error' in call"。怎么了？我找不到文档来进一步帮助我。

Answer 1

在第 2 步的顶部：创建 json...

添加这一行：

var err: NSError?

Answer 2

您可以通过这种方式完成。

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

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. 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！谢谢大家的意见！

调用中的额外参数 'error' - 无法构建我的 Xcode 项目

Extra argument 'error' in call - Unable to build my Xcode project

ios

json

swift

swift2

nsjsonserialization