swift 。为什么 dataTaskWithRequest 不调用闭包？

Question

这是我的代码:

let targetURL = NSURL(string: self.urlStringForRequestChannelDetails)
        let request = NSMutableURLRequest(URL: targetURL!)
        request.HTTPMethod = "GET"
        let defSession = NSURLSession.sharedSession()
        let task = defSession.dataTaskWithRequest(request, completionHandler: { (data: NSData?, response: NSURLResponse?, error: NSError?) -> Void in
                            let HTTPStatusCode = (response as! NSHTTPURLResponse).statusCode
                            if HTTPStatusCode == 200 && error == nil {
                                var resultsDict = [NSObject:AnyObject]()
                                do {
                                    resultsDict = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.AllowFragments) as! [NSObject:AnyObject]
                                } catch let caught as NSError {
                                    print(caught.description)
                                }
                                let items  = resultsDict["items"] as! [AnyObject]
                                let firstItemDict = items[0] as! [NSObject:AnyObject]

                                let snippetDict = firstItemDict["snippet"] as! [NSObject:AnyObject]
                                self.channelData["title"] = snippetDict["title"]
                                self.channelData["description"] = snippetDict["description"]

                                self.channelData["thumbnail"] = ((snippetDict["thumbnails"] as! [NSObject:AnyObject])["default"] as! [NSObject:AnyObject])["url"]
                                self.channelData["playlistId"] = ((firstItemDict["contentDetails"] as! [NSObject:AnyObject])["relatedPlaylists"] as! [NSObject:AnyObject])["uploads"]
                            } else {
                                print("HTTP Status Code = \(HTTPStatusCode)")
                                print("Error while loading channel details: \(error)")
                            }

        })
        task.resume()

我无法通过 brakepoint 在处理程序中停止执行，因为没有调用闭包。我做错了什么？

---

更新#1:

import Foundation

class YtDataManager {
    static var shared_instance = YtDataManager()



    let apiKey = "#################################"
    let #########ChannelName = "#########"
    var channelData = [NSObject:AnyObject]()
    var videosArray = [[NSObject:AnyObject]]()

    var playlistId: String { return self.channelData["playlistId"] as! String}
    var urlStringForRequestChannelDetails: String { return String("https://www.googleapis.com/youtube/v3/channels?part=contentDetails,snippet&forUsername=\(self.#########ChannelName)&key=\(self.apiKey)") }
    var urlStringForRequestChannelVideos: String { return String("https://www.googleapis.com/youtube/v3/playlistItems?part=snippet&playlistId=\(self.playlistId)&key=\(self.apiKey)") }


    func performGetRequest(targetURL: NSURL!, completion: (data: NSData?, HTTPStatusCode: Int, error: NSError?) -> Void) {
    }

    func get###ChannelDetails() {
        let targetURL = NSURL(string: self.urlStringForRequestChannelDetails)
        let request = NSMutableURLRequest(URL: targetURL!)
        request.HTTPMethod = "GET"
        let defSession = NSURLSession.sharedSession()
        let task = defSession.dataTaskWithRequest(request, completionHandler: { (data: NSData?, response: NSURLResponse?, error: NSError?) -> Void in

                            let HTTPStatusCode = (response as! NSHTTPURLResponse).statusCode
                            if HTTPStatusCode == 200 && error == nil {
                                var resultsDict = [NSObject:AnyObject]()
                                do {
                                    resultsDict = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.AllowFragments) as! [NSObject:AnyObject]
                                } catch let caught as NSError {
                                    print(caught.description)
                                }
                                let items  = resultsDict["items"] as! [AnyObject]
                                let firstItemDict = items[0] as! [NSObject:AnyObject]

                                let snippetDict = firstItemDict["snippet"] as! [NSObject:AnyObject]
                                self.channelData["title"] = snippetDict["title"]
                                self.channelData["description"] = snippetDict["description"]

                                self.channelData["thumbnail"] = ((snippetDict["thumbnails"] as! [NSObject:AnyObject])["default"] as! [NSObject:AnyObject])["url"]
                                self.channelData["playlistId"] = ((firstItemDict["contentDetails"] as! [NSObject:AnyObject])["relatedPlaylists"] as! [NSObject:AnyObject])["uploads"]
                            } else {
                                print("HTTP Status Code = \(HTTPStatusCode)")
                                print("Error while loading channel details: \(error)")
                            }

        })
        task.resume()


    }


    func getVideosFor###Channel() {
        let targetURL = NSURL(fileURLWithPath: self.urlStringForRequestChannelVideos)
        self.performGetRequest(targetURL, completion: { (data, HTTPStatusCode, error) -> Void in
            if HTTPStatusCode == 200 && error == nil {
                var resultsDict = [NSObject:AnyObject]()
                do {
                    resultsDict = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.AllowFragments) as! [NSObject:AnyObject]
                } catch let caught as NSError {
                    print(caught.description)
                }
                let items: Array<Dictionary<NSObject, AnyObject>> = resultsDict["items"] as! Array<Dictionary<NSObject, AnyObject>>

                // Use a loop to go through all video items.
                for var i=0; i<items.count; ++i {
                    let playlistSnippetDict = (items[i] as Dictionary<NSObject, AnyObject>)["snippet"] as! Dictionary<NSObject, AnyObject>

                    // Initialize a new dictionary and store the data of interest.
                    var desiredPlaylistItemDataDict = Dictionary<NSObject, AnyObject>()

                    desiredPlaylistItemDataDict["title"] = playlistSnippetDict["title"]
                    desiredPlaylistItemDataDict["thumbnail"] = ((playlistSnippetDict["thumbnails"] as! Dictionary<NSObject, AnyObject>)["default"] as! Dictionary<NSObject, AnyObject>)["url"]
                    desiredPlaylistItemDataDict["videoID"] = (playlistSnippetDict["resourceId"] as! Dictionary<NSObject, AnyObject>)["videoId"]

                    // Append the desiredPlaylistItemDataDict dictionary to the videos array.
                    self.videosArray.append(desiredPlaylistItemDataDict)

                    // Reload the tableview.
                    //self.tblVideos.reloadData()
                }
            } else {
                print("HTTP Status Code = \(HTTPStatusCode)")
                print("Error while loading channel videos: \(error)")
            }
        })
    }
}

请不要介意空函数。因为我已经开始变通，所以我试图让代码更简单。

---

更新#2:

import UIKit

class YtFeedViewController: UIViewController {
@IBOutlet weak var menuButton:UIBarButtonItem!

override func viewDidLoad() {
    super.viewDidLoad()

    if self.revealViewController() != nil {
        menuButton.target = self.revealViewController()
        menuButton.action = "revealToggle:"
        self.view.addGestureRecognizer(self.revealViewController().panGestureRecognizer())

        YtDataManager.shared_instance.get###ChannelDetails()
        print(YtDataManager.shared_instance.channelData.count) //0!
        YtDataManager.shared_instance.getVideosFor###Channel() 
    }

    self.navigationItem.title = "YouTube feed"
    // Do any additional setup after loading the view.
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

Answer 1

其实是这样的。我只是复制并粘贴您的代码，删除自定义逻辑并运行它。

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let targetURL = NSURL(string: "https://google.com")
        let request = NSMutableURLRequest(URL: targetURL!)
        request.HTTPMethod = "GET"
        let defSession = NSURLSession.sharedSession()
        let task = defSession.dataTaskWithRequest(request, completionHandler: { (data: NSData?, response: NSURLResponse?, error: NSError?) -> Void in
            print(response)

        })
        task.resume()
    }
}