请求超时 NSURLSession

Question

你好我使用下面的代码向服务器发送请求。如何在此函数中添加超时

static func postToServer(url:String,var params:Dictionary<String,NSObject>, completionHandler: (NSDictionary?, String?) -> Void ) -> NSURLSessionTask {


        let request = NSMutableURLRequest(URL: NSURL(string: url)!)


        let session = NSURLSession.sharedSession()

        request.HTTPMethod = "POST"

    if(params["data"] != "get"){
        do {

            let data = try NSJSONSerialization.dataWithJSONObject(params, options: .PrettyPrinted)

            let dataString = NSString(data: data, encoding: NSUTF8StringEncoding)!
            print("dataString is  \(dataString)")

            request.HTTPBody = data


        } catch {
            //handle error. Probably return or mark function as throws
            print("error is \(error)")
            //return
        }

    }
        request.addValue("application/json", forHTTPHeaderField: "Content-Type")
        request.addValue("application/json", forHTTPHeaderField: "Accept")

        let task = session.dataTaskWithRequest(request) {data, response, error -> Void in
            // handle error

            guard error == nil else { return }
            request.timeoutInterval = 10


           print("Response: \(response)")
            let strData = NSString(data: data!, encoding: NSUTF8StringEncoding)
             completionHandler(nil,"Body: \(strData!)")
          //print("Body: \(strData!)")

            let json: NSDictionary?
            do {
                json = try NSJSONSerialization.JSONObjectWithData(data!, options: .MutableLeaves) as? NSDictionary
            } catch let dataError {
                // Did the JSONObjectWithData constructor return an error? If so, log the error to the console
                print(dataError)
                let jsonStr = NSString(data: data!, encoding: NSUTF8StringEncoding)
              print("Error could not parse JSON: '\(jsonStr)'")
                completionHandler(nil,"Body: \(jsonStr!)")

                // return or throw?
                return
            }


            // The JSONObjectWithData constructor didn't return an error. But, we should still
            // check and make sure that json has a value using optional binding.
            if let parseJSON = json {
                // Okay, the parsedJSON is here, let's get the value for 'success' out of it

                completionHandler(parseJSON,nil)
                //let success = parseJSON["success"] as? Int
                //print("Succes: \(success)")
            }
            else {
                // Woa, okay the json object was nil, something went worng. Maybe the server isn't running?
                let jsonStr = NSString(data: data!, encoding: NSUTF8StringEncoding)
                print("Errors could not parse JSON: \(jsonStr)")
                completionHandler(nil,"Body: \(jsonStr!)")
            }

        }

        task.resume()
        return task
    }

我也搜索了一下，才知道要用这个功能

let request = NSURLRequest(URL: url!, cachePolicy: .ReloadIgnoringLocalAndRemoteCacheData, timeoutInterval: 5.0)

而不是这个

let request = NSMutableURLRequest(URL: NSURL(string: url)!)

但问题是，如果我使用上面的函数，那么我无法设置这些变量

request.HTTPBody = data
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
        request.addValue("application/json", forHTTPHeaderField: "Accept")

请任何人建议我如何在我的函数中添加超时的正确解决方案

Answer 1

NSMutableURLRequest 也有这个方法：

let request = NSMutableURLRequest(URL:  NSURL(string: url)!, cachePolicy: .ReloadIgnoringLocalAndRemoteCacheData, timeoutInterval: 5)

Answer 2

您无法修改您的请求，因为出于某种原因您选择了不可变选项。由于 NSMutableURLRequest 是 NSURLRequest 的子类，您可以使用完全相同的初始化程序 init(URL:cachePolicy:timeoutInterval:) 来创建 mutable 实例并设置默认超时。然后根据需要配置（改变）这个请求。

let request = NSMutableURLRequest(URL: url!, cachePolicy: .ReloadIgnoringLocalAndRemoteCacheData, timeoutInterval: 5.0)

Answer 3

使用NSURLSessionConfiguration指定超时，

let sessionConfig = NSURLSessionConfiguration.defaultSessionConfiguration()
sessionConfig.timeoutIntervalForRequest = 30.0 //Request Timeout interval 30 sec
sessionConfig.timeoutIntervalForResource = 30.0 //Response Timeout interval 30 sec

let session  = NSURLSession(configuration: sessionConfig)

Answer 4

NSMutableRequest 有一个属性 timeoutInterval 可以设置。 Here 是 Apple 的文档，向您展示了如何设置超时。

他们说

If during a connection attempt the request remains idle for longer than the timeout interval, the request is considered to have timed out. The default timeout interval is 60 seconds.

请注意，超时确实不保证如果网络调用网络调用将被终止未 在超时时间内完成。

即：假设您将超时设置为 60 秒。连接可能仍处于活动状态，并且在 60 秒后不会终止。如果在 60 秒的完整时间内没有数据传输，则会发生超时。

E.g. Consider the following scenario This does NOT incur a timeout

t=0 到 t=59 秒 => 无数据传输 （总共 59 秒）
t=60 到 t=62 => 一些数据在 t=60 秒到达 （总共 2 秒）
t=63 到 t=100 => 无数据传输（总共 37 秒）
t=100 to t=260 => 剩余数据传输并完成网络请求 （总计 160 秒）

Now consider the following scenario. Timeout occurs at t=120

t=0 到 t=59 秒 => 一些数据传输直到 t=59 （总共 59 秒）
t=60 到 t=120 => 无数据传输（总共 60 秒）

请求超时 NSURLSession

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