dataTaskWithURL的completionHandler仅在请求失败时调用

Question

我需要一个带代理的NSURLSession，因为我必须实现它的

public func URLSession(session: NSURLSession, didReceiveChallenge challenge: NSURLAuthenticationChallenge, completionHandler: (NSURLSessionAuthChallengeDisposition, NSURLCredential?) -> Void) {}

委托加载我自己的CA证书的方法。

我还想用dataTaskWithURL 与completionHandler打电话，因为我在调用的方法中将completionHandler作为闭包参数。

public func call(hostName:String, completion: (responsedata : NSData?, response : NSURLResponse?, error : NSError?) -> Void){

    let sessionConfiguration = NSURLSessionConfiguration.defaultSessionConfiguration()
    sessionConfiguration.HTTPCookieStorage = NSHTTPCookieStorage.sharedHTTPCookieStorage()
    sessionConfiguration.timeoutIntervalForRequest = 8;
    let session = NSURLSession(configuration: sessionConfiguration, delegate: self, delegateQueue: nil)
    let requestURL = NSURL(string:"https://myhost.com/call")

    session.dataTaskWithURL(requestURL!, completionHandler: completion).resume()
}

问题是只有在请求超时或失败时才会调用completionHandler。如果成功，它永远不会被调用。有谁知道为什么？

我的completionHandler代码：

call("myhost.com",  completion: {
        (responsedata : NSData?, response : NSURLResponse?, error : NSError?) in
        var newConnectionStatus: Bool
        if let httpResponse = response as? NSHTTPURLResponse{

            if error == nil {
                if (httpResponse.statusCode == 200)
                {
                    newConnectionStatus = true
                }
                else
                {
                    newConnectionStatus = false
                }
            }
            else{
                newConnectionStatus = false
            }
        }else{
            newConnectionStatus = false
        }

        if newConnectionStatus != scpGlobalVariables.sharedInstance().currentConnectivityStatus{
            scpGlobalVariables.sharedInstance().currentConnectivityStatus = newConnectionStatus
            NSNotificationCenter.defaultCenter().postNotificationName("ConnectionStateChangedNotification", object: self, userInfo: ["connectivityStatus":NSNumber(bool: newConnectionStatus)])

        }

        if newConnectionStatus == true{
            sleep(5)
            self.runConnectionChecker()
        }else{
            sleep(0);
            self.runConnectionChecker()
        }


    })

只有在调用completionHandler时，response和responsedata为零