ios - NSURLSession didCompleteWithError : how to determine what task it is?

Question

我有一个符合用于下载数据的 NSURLSession 委托(delegate)的类，当完成调用方法 func URLSession(session: NSURLSession, task: NSURLSessionTask, didCompleteWithError error: NSError?) ，结果在这里被解析和处理以返回到正确的 View Controller 。

我如何知道结果来自哪个 session 或任务，以便调用正确的 View Controller ？

import Foundation


class Support{

// MARK - Properties
var ID: Int!
var SoftekID: String!
var Subject: String!
var LastUpdate: String!
var LastUpdatedBy: String!
var Priority: Int!
var Impact: Int!
var SupportType: String!
var Importance: Int!


// MARK: General
init() {
    self.ID = 0
    self.SoftekID = ""
    self.Subject = ""
    self.LastUpdate = ""
    self.LastUpdatedBy = ""
    self.Priority = 0
    self.Impact = 0
    self.SupportType = ""
    self.Importance = 0
}

func getSupportTickets(){
let sp = SuppportProvider()
    sp.getSupportTickets()
}
}

class SuppportProvider: NSObject, NSURLSessionDelegate,      NSURLSessionDataDelegate, NSURLSessionTaskDelegate{

// MARK: - Properties
var mData: NSMutableData?
var session: NSURLSession!

override init(){
    super.init()
    prepareConnection()
}

// MARK: - Methods
func prepareConnection(){

    session = NSURLSession(configuration: NSURLSessionConfiguration.defaultSessionConfiguration(), delegate: self, delegateQueue:nil)
}

func getSupportTickets(){
    var request = NSMutableURLRequest(URL: NSURL(string: "http://10.0.58.137/ISOWeb.UI/api/CSMobile/GetSupportTickets?PageNumber=0&PagingSize=10&TicketStatus=Priority")!,
        cachePolicy: NSURLRequestCachePolicy.UseProtocolCachePolicy,
        timeoutInterval: 20.0)

    let task =  session.dataTaskWithRequest(request)

    mData = NSMutableData()
    task.resume()
}

func getHelpInformation(){
    var request = NSMutableURLRequest(URL: NSURL(string: "http://10.0.58.137/ISOWeb.UI/api/CSMobile/GetHelpInformation")!,
        cachePolicy: NSURLRequestCachePolicy.UseProtocolCachePolicy,
        timeoutInterval: 20.0)

    let task = session.dataTaskWithRequest(request)

    mData = NSMutableData()
    task.resume()
}

func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, didReceiveResponse response: NSURLResponse, completionHandler: (NSURLSessionResponseDisposition) -> Void) {

    mData!.length = 0
    completionHandler(NSURLSessionResponseDisposition.Allow)
}

func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, didReceiveData data: NSData) {

    mData!.appendData(data)
}

func URLSession(session: NSURLSession, task: NSURLSessionTask, didCompleteWithError error: NSError?) {

    if error != nil{
        println("An error has occured completing the request")
    }else{

        //Result for method: getSupportTickets
        var value = NSString(bytes: mData!.mutableBytes, length: mData!.length, encoding: NSUTF8StringEncoding)

        var jError: NSError?

        if let JSONResult: Array<NSDictionary> = NSJSONSerialization.JSONObjectWithData(mData!, options: NSJSONReadingOptions.AllowFragments, error: &jError) as? Array<NSDictionary> {

            if JSONResult.count > 0 {

               var arr = Array<Support>()

                for dict in JSONResult{

                    let item = Support()

                    if (dict["ID"] as? Int != nil) {
                        item.ID = dict["ID"] as! Int
                    }else {
                        item.ID = 0
                    }

                    if (dict["SoftekID"] as? String != nil) {
                        item.SoftekID = dict["SoftekID"] as! String
                    }else {
                        item.SoftekID = ""
                    }

                    if (dict["Subject"] as? String != nil) {
                        item.Subject = dict["Subject"] as! String
                    }else {
                        item.Subject = ""
                    }

                    if (dict["LastUpdate"] as? String != nil) {
                          item.LastUpdate = dict["LastUpdate"] as! String
                    }else {
                        item.LastUpdate = ""
                    }

                    if (dict["LastUpdatedBy"] as? String != nil) {
                         item.LastUpdatedBy = dict["LastUpdatedBy"] as! String
                    }else {
                        item.LastUpdatedBy = ""
                    }

                    if (dict["Priority"] as? Int != nil) {
                         item.Priority = dict["Priority"] as! Int
                    }else {
                         item.Priority = 0
                    }

                    if (dict["Impact"] as? Int != nil) {
                        item.Impact = dict["Impact"] as! Int
                    }else {
                        item.Impact = 0
                    }

                    if (dict["SupportType"] as? String != nil) {
                         item.SupportType = dict["SupportType"] as! String
                    }else {
                        item.SupportType = ""
                    }

                    if (dict["Importance"] as? Int != nil) {
                        item.Importance = dict["Importance"] as! Int
                    }else {
                        item.Importance = 0
                    }

                    arr.append(item)
                }
            }
        }

        //Result for method: getHelpInformation
        //How to know to which task holds the result?
    }
}

}

更新

import Foundation

class CSSupport{

// MARK - Properties
var ID: Int!
var SoftekID: String!
var Subject: String!
var LastUpdate: String!
var LastUpdatedBy: String!
var Priority: Int!
var Impact: Int!
var SupportType: String!
var Importance: Int!


// MARK: General
init() {
    self.ID = 0
    self.SoftekID = ""
    self.Subject = ""
    self.LastUpdate = ""
    self.LastUpdatedBy = ""
    self.Priority = 0
    self.Impact = 0
    self.SupportType = ""
    self.Importance = 0
}
}

class Support:NSObject, NSURLSessionDelegate, NSURLSessionDataDelegate, NSURLSessionTaskDelegate{

// MARK: - Properties
var mData: NSMutableData?
var session: NSURLSession!

 override init(){
    super.init()
    var configuration = NSURLSessionConfiguration.defaultSessionConfiguration()
    session = NSURLSession(configuration:configuration, delegate: self, delegateQueue:nil)
}

// MARK: - Methods
func getSupportTickets(){
    var request = NSMutableURLRequest(URL: NSURL(string: "http://10.0.58.137/ISOWeb.UI/api/CSMobile/GetSupportTickets?PageNumber=0&PagingSize=10&TicketStatus=Priority")!,
        cachePolicy: NSURLRequestCachePolicy.UseProtocolCachePolicy,
        timeoutInterval: 20.0)

    let task =  session.dataTaskWithRequest(request)

    mData = NSMutableData()
    task.resume()
}

func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, didReceiveResponse response: NSURLResponse, completionHandler: (NSURLSessionResponseDisposition) -> Void) {

    mData!.length = 0
    completionHandler(NSURLSessionResponseDisposition.Allow)
}

func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, didReceiveData data: NSData) {

    mData!.appendData(data)
}

func URLSession(session: NSURLSession, task: NSURLSessionTask, didCompleteWithError error: NSError?) {

    if error != nil{
        println("An error has occured completing the request")
    }else{

         var value = NSString(bytes: mData!.mutableBytes, length: mData!.length, encoding: NSUTF8StringEncoding)
         var jError: NSError?

        switch task.taskIdentifier {
        case 1:
            if let JSONResult: Array<NSDictionary> = NSJSONSerialization.JSONObjectWithData(mData!, options: NSJSONReadingOptions.AllowFragments, error: &jError) as? Array<NSDictionary> {

                if JSONResult.count > 0 {

                    var arr = Array<CSSupport>()

                    for dict in JSONResult{

                        let item = CSSupport()

                        if (dict["ID"] as? Int != nil) {
                            item.ID = dict["ID"] as! Int
                        }else {
                            item.ID = 0
                        }

                        if (dict["SoftekID"] as? String != nil) {
                            item.SoftekID = dict["SoftekID"] as! String
                        }else {
                            item.SoftekID = ""
                        }

                        if (dict["Subject"] as? String != nil) {
                            item.Subject = dict["Subject"] as! String
                        }else {
                            item.Subject = ""
                        }

                        if (dict["LastUpdate"] as? String != nil) {
                            item.LastUpdate = dict["LastUpdate"] as! String
                        }else {
                            item.LastUpdate = ""
                        }

                        if (dict["LastUpdatedBy"] as? String != nil) {
                            item.LastUpdatedBy = dict["LastUpdatedBy"] as! String
                        }else {
                            item.LastUpdatedBy = ""
                        }

                        if (dict["Priority"] as? Int != nil) {
                            item.Priority = dict["Priority"] as! Int
                        }else {
                            item.Priority = 0
                        }

                        if (dict["Impact"] as? Int != nil) {
                            item.Impact = dict["Impact"] as! Int
                        }else {
                            item.Impact = 0
                        }

                        if (dict["SupportType"] as? String != nil) {
                            item.SupportType = dict["SupportType"] as! String
                        }else {
                            item.SupportType = ""
                        }

                        if (dict["Importance"] as? Int != nil) {
                            item.Importance = dict["Importance"] as! Int
                        }else {
                            item.Importance = 0
                        }

                        arr.append(item)
                    }
                }
            }
            break

        case 2:

            break

        default:
            println("No task was found.")
            break
        }
    }
}

}

Answer 1

是的，缺少任何类型的可定制存储有点烦人，特别是因为标识符仅在每个 session 的基础上是唯一的。有几种方法可以解决这个问题:

• 如果您正在使用后台 session 或前景和后台 session 的混合，我认为您可以做的最好的事情是两级查找，其中您将可变字典与每个 session 相关联并查找首先是 session ，然后通过 session 字典中的标识符查找任务:

  • 对于后台 session ，提供一个标识符以用作顶级可变字典中的键。
  • 对于其他 session ，使用 session 对象本身作为顶级可变字典中的键。

• 如果您仅使用前台任务(即不在后台 session 中)，您应该能够将任务用作字典键并查找与任务相关的其他数据。

我认为这两种技术应该都能正常工作。您还可以使用任务中的关联对象来存储额外数据(只要您不使用后台 session )。

你绝对不能做的一件事(我已经提交了一个关于这个的错误)是子类 NSURLRequest 并在那里存储额外的数据，因为当你请求 currentRequest 时 NSURLSession 返回它自己的 NSURLRequest 副本(而不是你的自定义子类) ，并在您请求 orginalRequest 时返回您的子类的看似随机的实例(与实际的原始请求无关)。

令人惊奇的是，每个人都必须付出多少努力来创建外部词典来解决每个任务和每个 session 中缺少简单 refCon 对象属性的问题。提交错误以请求该功能绝对值得。